Research ArticleProduction and Decay of Up-Type and Down-Type New HeavyQuarks through Anomalous Interactions at the LHC
E T CcedilakJr1 S Kuday1 and O CcedilakJr12
1Application and Research Center for Advanced Studies Istanbul Aydin University Sefakoy 34295 Istanbul Turkey2Department of Physics Ankara University Tandogan 06100 Ankara Turkey
Correspondence should be addressed to I T Cakır ilkayturkcakircernch
Received 23 October 2014 Revised 19 January 2015 Accepted 26 January 2015
Academic Editor Hong-Jian He
Copyright copy 2015 I T Cakır et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited Thepublication of this article was funded by SCOAP3
We study the process 119901119901 rarr 119876119881 + 119883 (where 119876 = 119905 119887 and 119881 = 119892 120574 and 119885) through the anomalous interactions of the newheavy quarks at the LHC Considering the present limits on the masses and mixings the signatures of the heavy quark anomalousinteractions are discussed and analysed at the LHC for the center of mass energy of 13 TeV An important sensitivity to anomalouscouplings 120581119905
1015840
119892Λ = 010TeVminus1 120581119905
1015840
120574Λ = 014TeVminus1 120581119905
1015840
119885Λ = 019TeVminus1 and 120581119887
1015840
119892Λ = 015TeVminus1 120581119887
1015840
119885Λ = 019TeVminus1 120581119887
1015840
120574Λ =
030TeVminus1 for the mass of 750GeV of the new heavy quarks 1199051015840 and 1198871015840 can be reached for an integrated luminosity of 119871 int = 100fbminus1
1 Introduction
The standard model (SM) of the strong and electroweakinteractions describes successfully the phenomena of particlephysics However there are many unanswered questionssuggesting the SM to be an effective theory In order to answersome of the problems with the SM additional new fermionscan be accommodated in many models beyond the SM (see[1ndash9] and references therein) The new heavy quarks couldalso be produced in pairs at the LHC with center of massenergy of 13 TeV However due to the expected smallness ofthemixing between the newheavy quarks and known quarksthe decay modes can be quite different from the one relevantto charged weak interactions A new symmetry beyond theSM is expected to explain the smallness of these mixingsThearguments given in [10] for anomalous interactions of the topquark are more valid for the new heavy quarks 1199051015840 and 1198871015840 dueto their expected larger masses than the top quark
The ATLAS experiment [11] and CMS experiment [12]have searched for the fourth generation of quarks and setlimits on the mass of 119898
1198871015840 gt 480GeV and 119898
1199051015840 gt 570GeV at
radic119904 = 7TeV The pair production of new heavy quarks hasbeen searched by the ATLAS experiment [13 14] and the1198981199051015840 gt 656GeV mass limits are set at radic119904 = 7TeV The CMS
experiment has excluded 1199051015840 masses below 557GeV [15] Thevector-like quarks have been searched by the ATLAS experi-ment [16 17] and set bounds as 900GeV for charged currentchannel and 760GeV for neutral current channel at radic119904 =7TeVThe CMS experiment [18] has set the lower bounds onthe mass of 685GeV at radic119904 = 8TeV Some of the final statesin the searches of new phenomena can also be considered inrelation with the new heavy quarks
The anomalous resonant productions of the fourth familyquarks have been studied in [19 20] at the LHC with radic119904 =14TeV The possible single productions of fourth generationquarks via anomalous interactions at Tevatron have also beenstudied in [21] The parameter space for the mixing of thefourth generation quarks has been presented in [22] TheCP violating flavor changing neutral current processes ofthe fourth generation quarks have been analyzed in [23]and the large mixing between fourth generation and firstthree generations has been excluded under the proposed fitconditions Investigation of the parameter space favored bythe precision electroweak data has been performed for thefourth SM family fermions in [24]
In this work we present the analysis of anomalous pro-ductions and decay of new heavy quarks 1199051015840 and 1198871015840 at the LHCWe have performed the fast simulation for the signal and
Hindawi Publishing CorporationAdvances in High Energy PhysicsVolume 2015 Article ID 134898 14 pageshttpdxdoiorg1011552015134898
2 Advances in High Energy Physics
background Any observations of the invariant mass peak inthe range of 500ndash1000GeV and excess in the events with thefinal states originating from119882119887119881 and 119887119881 can be interpretedas the signal for the new heavy quarks 1199051015840 and 1198871015840 via theanomalous interactions
2 New Heavy Quarks Anomalous Interactions
A general theory that includes the standard model (SM) asits low energy limit can be written as an expansion seriesin powers of Λminus1 with operators obeying the required sym-metries The dimension six gauge invariant operators can bebuilt from the SM fields and they can induce dimension fiveoperators after spontaneous symmetry breaking The coef-ficients of the dimension five terms are related to those ofdimension six operators and they can lead to sizable effects inthe heavy quark associated production in high energy col-lisions [25] For our study the effective Lagrangian withdimension five terms for the anomalous interactions amongthe new heavy quarks (1198761015840 equiv 1199051015840 or 1198871015840) ordinary quarks 119902 andthe gauge bosons 119881 = 120574 119885 119892 can be written explicitly
119871 = sum
119902119894=119906119888119905
120581119902119894
120574
Λ119876119902119894
1198921198901199051015840
120590120583]119902119894119865120583]+ sum
119902119894=119906119888119905
120581119902119894
119911
2Λ1198921199111199051015840
120590120583]119902119894119885120583]
+ sum
119902119894=119906119888119905
120581119902119894
119892
2Λ1198921199041199051015840
120590120583]120582119886119902119894119866
120583]119886+ sum
119902119894=119889119904119887
120581119902119894
120574
Λ119876119902119894
1198921198901198871015840
120590120583]119902119894119865120583]
+ sum
119902119894=119889119904119887
120581119902119894
119911
2Λ1198921199111198871015840
120590120583]119902119894119885120583]+ sum
119902119894=119889119904119887
120581119902119894
119892
2Λ1198921199041198871015840
120590120583]120582119886119902119894119866
120583]119886
+ hc(1)
where 119865120583] 119885120583] and 119866120583] are the field strength tensors of thegauge bosons 120590
120583] = 119894(120574120583120574] minus 120574]120574120583)2 120582119886 are the Gell-Mannmatrices119876
119902is the electric charge of the quark (119902) 119892
119890 119892119885 and
119892119904are the electromagnetic neutral weak and strong coupling
constants respectively 119892119885= 119892119890 cos 120579
119908sin 120579119908 where 120579
119908is
the weak mixing angle 120581120574is the anomalous coupling with
photon 120581119911is for the 119885 boson and 120581
119892is the coupling with
gluon Finally Λ is the cutoff scale for the new interactions
3 Decay Widths and Branchings
For the decay channels 1198761015840 rarr 119881119902 where 119881 equiv 120574 119885 and 119892 weuse the effective Lagrangian to calculate the anomalous decaywidths
Γ (1198761015840997888rarr 119892119902) =
2
3(120581119902
119892
Λ)
2
1205721199041198983
11987610158401205820
Γ (1198761015840997888rarr 120574119902) =
1
2(120581119902
120574
Λ)
2
1205721198901198762
1199021198983
11987610158401205820
Γ (1198761015840997888rarr 119885119902) =
1
16(120581119902
119885
Λ)
21205721198901198983
1198761015840
sin2120579119882cos2120579119882
120582119885radic120582119903
(2)
Table 1 Branching ratios () and decay width of the new heavyquark (1199051015840) with only anomalous interactions for PI parametrizationand 120581Λ = 01 TeVminus1
The anomalous decay widths in different channels areproportional to Λminus2 and they are assumed to be dominantfor 120581Λ gt 01TeVminus1 over the charged current channels Inthis case if we take all the anomalous coupling equal then thebranching ratios will be nearly independent of 120581Λ We haveused three parametrization sets entitled PI PII and PIII Forthe PI parametrization we assume the constant value 120581
119894Λ =
01TeVminus1 and PII has the parameters 120581119894Λ = 01120582
4minus119894 TeVminus1with 120582 = 05 For PIII we take the couplings 120581
119894Λ =
051205824minus119894 TeVminus1 with the same value of 120582 The index 119894 is the
generation numberTables 1 and 2 present the decay width and branching
ratios of the new heavy quark 1199051015840 through anomalous inter-actions for the parametrization PI PII and PIII respectivelyTaking the anomalous coupling 120581Λ = 01TeVminus1 we calculatethe 1199051015840 decay width Γ = 065GeV and 190GeV for 119898
1199051015840 =
700GeV and 1000GeV respectivelyThe branching into 1199051015840 rarr119902119892 channel is the largest and branching into 1199051015840 rarr 119902120574
channel is the smallest for equal anomalous couplings withthe parametrization PI On the other hand PII and PIIIparametrization give higher branching ratios into 119905119881 (119881 =
119892 119885 120574) than 119902119881 (119902 = 119906 119888) channels due to 1205824minus119894 factor in theparametrization
For the new heavy quark 1198871015840 the decay width and branch-ing ratios are presented in Tables 3 and 4 for the parametriza-tions PI PII and PIII respectively We calculate the 1198871015840 decaywidth by taking the anomalous couplings 120581Λ = 01TeVminus1Γ = 068GeV and 192GeV for119898
1198871015840 = 700GeV and 1000GeV
respectively The branching for 1198871015840 rarr 119902119892 is the largest (30)and it is the smallest for 1198871015840 rarr 119902120574 (02) channel for equalanomalous couplings with the parametrization PI For PII
Advances in High Energy Physics 3
Table 2 The same as Table 1 but for PII (PIII) parametrization
Figure 1 Diagrams for the subprocess 119892119902 rarr 119881119876 with anomalous vertices 1198761015840119902119881 and 1198761015840119876119881 (where 1198761015840 can be the new heavy quark 1198871015840 or 1199051015840depending on the type of light (119902) or heavy (119876 equiv 119905 119887) quarks resp)
Table 3 Branching ratios () and decay width of the new heavyquark (1198871015840) with only anomalous interactions for PI parametrizationand 120581Λ = 01 TeVminus1
and PIII parametrization the branching ratios into 119887119881 (119881 =
119892 119885 120574) are larger than 119902119881 (119902 = 119889 119904) channels The 1199051015840 and1198871015840 decay widths are about the same values for PII and PIIIparametrization
4 The Cross Sections
In order to study the new heavy quark productions at theLHC we have used effective anomalous interaction verticesand implemented these vertices into the CalcHEP package[26] In all of the numerical calculations the parton dis-tribution functions are set to the CTEQ6L parametrization[27] The new heavy quarks can be produced through theiranomalous couplings to the ordinary quarks and neutralvector bosons as shown in Figure 1
Total cross sections for the productions of new heavyquarks 1199051015840 and 119887
1015840 are given in Tables 5 and 6 for theparametrizations PI PII and PIII at the center of massenergy of 8 TeV and 13 TeV For an illustration taking themass of new heavy quarks as 700GeV the cross section of1199051015840(1198871015840) production is calculated as 850 pb (1003 pb) for the
parametrization PIII at radic119904 = 13TeV It can be seen fromTables 5 and 6 that the cross section decreases while the
PIIIPIPII
10minus1
100
101
102
500 600 700 800 900 1000
120590(p
b)
Mt998400 (GeV)
Figure 2The cross section for the process 119901119901 rarr 119905119881+119883 dependingon the mass for parameter sets PI PII and PIII at the center of massenergyradic119904 = 13TeV
mass of the new heavy quark increases The cross section for1199051015840 production is larger than the 1198871015840 production with a factor of12ndash18 (07ndash10) for PI (PII and PIII) parametrization depend-ing on the consideredmass range atradic119904 = 13TeVThe generalbehaviour of the production cross sections depending on themass of new heavy quarks is presented in Figures 2 and 3 fordifferent parametrizations
41 Analysis of the Process 119901119901 rarr 119882+119887119881+119883 (119881 = 119892 119885 120574) for
1199051015840 Signal The signal process 119901119901 rarr 119882
includes the 1199051015840 exchange in both the 119904-channel and 119905-channelThe 119904-channel contribution to the signal process wouldappear itself as resonance around the 1199051015840 mass value in the119882119887119881 invariant mass The 119905-channel gives the nonresonant
4 Advances in High Energy Physics
Table 4 The same as Table 3 but for PII (PIII) parametrization
Table 5The cross sections (in pb) of new heavy quark 1199051015840 production without cuts for PI PII and PIII parametrizations at the center of massenergy 13TeV (8TeV) respectively
Mass (GeV) PI PII PIIIradic119904 = 13 TeV (8 TeV) radic119904 = 13 TeV (8 TeV) radic119904 = 13 TeV (8 TeV)
Figure 3The cross section for the process119901119901 rarr 119887119881+119883 dependingon the new heavy quark mass for parameter sets PI PII and PII atthe center of mass energyradic119904 = 13TeV
contribution We consider that the 119882 boson decays intolepton + missing transverse momentum with the branchingratio of 21 and 119885 boson decays into dilepton with thebranching ratio of 67 In our analyses we consider the 1199051015840signal in the 119897 + 119887jet + 120574 + MET 119897 + 119887jet + 119895 + MET and3119897 + 119887jet +MET channels where 119897 = 119890 120583 However if one takesthe hadronic119882 decay the signal will be enhanced by a factorof BR(119882 rarr hadrons)BR(119882 rarr 119897])
We have obtained the cross sections by using the cutspseudorapidity |120578
119895120574| lt 25 and transverse momentum 119901
119895120574
119879gt
20ndash200GeV for jets and photon in Table 7 (Tables 8 and 9)
500 600 700 800 900 100010minus6
10minus5
10minus4
10minus3
10minus2
10minus1
100
d120590d
mtV
(pb
GeV
)
MtV (GeV)
pp rarr tg + X
pp rarr tZ + X
pp rarr t120574 + X
Figure 4 Invariant mass distributions 119898119905119881
(where 119881 = 120574 119892 and119885) for PI parametrization of the signal with 120581Λ = 02TeVminus1 and1198981199051015840 = 700GeV at the center of mass energy radic119904 = 13TeV
for PI (PII PIII) parametrization respectively Invariantmassdistribution of the 119905119881 (where 119881 = 120574 119892 and 119885) system isshown in Figure 4 for PI parametrization of the signal with120581Λ = 02TeVminus1 and 119898
1199051015840 = 700GeV at the center of mass
energy radic119904 = 13TeV It appears from signal significance cal-culations that the optimized transverse momentum cut is119901119895120574
119879gt 100GeV for 1199051015840 analysesThe backgrounds for the final state119882+119887(119887)119881 (where 119881 equiv
photon jet and 119885 boson) are given in Table 10 We apply thefollowing cuts to the final state photon and jets as |120578
119895120574| lt 25
and 119901119895120574119879
gt 20ndash200GeV For the background cross section
Advances in High Energy Physics 5
Table 6The cross sections (in pb) of new heavy quark 1198871015840 production without cuts for PI PII and PIII parametrizations at the center of massenergy of 13TeV (8TeV) respectively
Mass (GeV) PI PII PIIIradic119904 = 13 TeV (8 TeV) radic119904 = 13 TeV (8 TeV) radic119904 = 13 TeV (8 TeV)
Table 7 The cross sections (in pb) for 1199051015840 signal in different decay channels for PI parametrization with 119901119879cuts on the jets and photon and
|120578119895120574| lt 25 at the center of mass energyradic119904 = 13TeV
SignalMass (GeV)
PI119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119882+119887120574 + 119883
500 289 times 10minus1
210 times 10minus1
124 times 10minus1
102 times 10minus4
600 243 times 10minus1
164 times 10minus1
119 times 10minus1
123 times 10minus2
700 168 times 10minus1
12 times 10minus1
112 times 10minus1
225 times 10minus2
800 130 times 10minus1
103 times 10minus1
753 times 10minus2
325 times 10minus2
900 102 times 10minus1
808 times 10minus2
696 times 10minus2
302 times 10minus2
1000 761 times 10minus2
635 times 10minus2
507 times 10minus2
294 times 10minus2
119901119901 rarr 119882+119887119892 + 119883
500 778 times 100
602 times 100
363 times 100
474 times 10minus3
600 630 times 100
518 times 100
313 times 100
258 times 10minus1
700 499 times 100
363 times 100
304 times 100
932 times 10minus1
800 401 times 100
345 times 100
276 times 100
991 times 10minus1
900 332 times 100
277 times 100
213 times 100
108 times 100
1000 258 times 100
227 times 100
188 times 100
101 times 100
119901119901 rarr 119882+119887119885+119883
500 796 times 10minus1
601 times 10minus1
301 times 10minus1
101 times 10minus4
600 479 times 10minus1
386 times 10minus1
245 times 10minus1
271 times 10minus3
700 399 times 10minus1
312 times 10minus1
239 times 10minus1
696 times 10minus2
800 331 times 10minus1
289 times 10minus1
209 times 10minus1
805 times 10minus2
900 273 times 10minus1
273 times 10minus1
191 times 10minus1
954 times 10minus2
1000 223 times 10minus1
202 times 10minus1
161 times 10minus1
910 times 10minus2
estimates we assume the efficiency for 119887-tagging to be 120576119887=
50 and the rejection ratios to be 10 for 119888 (119888) quark jets and1 for light quark jets since they are assumed to bemistaggedas 119887-jets
In order to find the discovery limits we use the statisticalsignificance [28] defined as
where 119878 and 119861 are the numbers of the signal and backgroundevents respectively In Figures 5ndash7 the integrated luminosityrequired to reach 3120590 significance for the signal of 1199051015840 anoma-lous interactions is shown for parametrizations PI PII andPIII at the LHC with radic119904 = 13 TeV It is seen from these
figures that the channel 1199051015840 rarr 119905119885 requires more integratedluminosity than the other channels By requiring the signalsignificance 119878119878 = 3 the contour plots of 120581Λ and mass of1199051015840 quark are presented in Figure 8 The results show that onecan discover the 1199051015840 quark anomalous couplings 120581Λ down to01 TeVminus1 in the 119905119892 channel for119898
1199051015840 = 750GeV
411 Simulation for 1199051015840 Signal In order to include detectoreffects in the simulation we have generated 119905119881 (where 119881 =
120574 119892 and 119885) signal events for each subprocess and they aremixed using the ldquoevent mixerrdquo script which can be foundwithin the CALCHEP package [26] For further decay andhadronization these events are passed to PYTHIA [29] andsimulated with the PGS4 program [30] using generic LHC
6 Advances in High Energy Physics
Table 8 The same as Table 7 but for parametrization PII
SignalMass (GeV)
PII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119882+119887120574 + 119883
500 678 times 10minus3
507 times 10minus3
345 times 10minus3
264 times 10minus7
600 657 times 10minus3
542 times 10minus3
347 times 10minus3
534 times 10minus4
700 502 times 10minus3
431 times 10minus3
304 times 10minus3
873 times 10minus4
800 391 times 10minus3
376 times 10minus3
256 times 10minus3
103 times 10minus3
900 303 times 10minus3
268 times 10minus3
211 times 10minus3
101 times 10minus3
1000 240 times 10minus3
243 times 10minus3
177 times 10minus3
998 times 10minus4
119901119901 rarr 119882+119887119892 + 119883
500 347 times 10minus1
268 times 10minus1
152 times 10minus1
530 times 10minus6
600 251 times 10minus1
212 times 10minus1
135 times 10minus1
201 times 10minus2
700 187 times 10minus1
16 times 10minus1
116 times 10minus1
342 times 10minus2
800 146 times 10minus1
125 times 10minus1
939 times 10minus2
403 times 10minus2
900 112 times 10minus1
108 times 10minus1
780 times 10minus2
386 times 10minus2
1000 935 times 10minus2
837 times 10minus2
662 times 10minus2
368 times 10minus2
119901119901 rarr 119882+119887119885+119883
500 210 times 10minus2
177 times 10minus2
116 times 10minus2
264 times 10minus7
600 195 times 10minus2
175 times 10minus2
114 times 10minus2
134 times 10minus3
700 173 times 10minus2
143 times 10minus2
100 times 10minus2
29 times 10minus3
800 134 times 10minus2
119 times 10minus2
889 times 10minus3
342 times 10minus3
900 106 times 10minus2
955 times 10minus3
763 times 10minus3
337 times 10minus3
1000 809 times 10minus3
758 times 10minus3
631 times 10minus3
323 times 10minus3
Table 9 The same as Table 7 but for parametrization PIII
SignalMass (GeV)
PIII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119882+119887120574 + 119883
500 260 times 10minus1
278 times 10minus1
108 times 10minus1
159 times 10minus4
600 178 times 10minus1
161 times 10minus1
101 times 10minus1
142 times 10minus2
700 156 times 10minus1
135 times 10minus1
933 times 10minus2
272 times 10minus2
800 117 times 10minus1
106 times 10minus1
784 times 10minus2
332 times 10minus2
900 904 times 10minus2
842 times 10minus2
668 times 10minus2
325 times 10minus2
1000 760 times 10minus2
676 times 10minus2
516 times 10minus2
317 times 10minus2
119901119901 rarr 119882+119887119892 + 119883
500 839 times 100
649 times 100
386 times 100
465 times 10minus3
600 610 times 100
578 times 100
381 times 100
556 times 10minus1
700 539 times 100
464 times 100
341 times 100
970 times 10minus1
800 394 times 100
354 times 100
273 times 100
105 times 100
900 324 times 100
276 times 100
227 times 100
107 times 100
1000 233 times 100
229 times 100
184 times 100
998 times 10minus1
119901119901 rarr 119882+119887119885+119883
500 772 times 10minus1
101 times 100
217 times 10minus1
627 times 10minus4
600 624 times 10minus1
385 times 10minus1
292 times 10minus1
320 times 10minus2
700 500 times 10minus1
305 times 10minus1
286 times 10minus1
580 times 10minus2
800 378 times 10minus1
250 times 10minus1
242 times 10minus1
964 times 10minus2
900 304 times 10minus1
167 times 10minus1
206 times 10minus1
962 times 10minus2
1000 251 times 10minus1
129 times 10minus1
148 times 10minus1
961 times 10minus2
Advances in High Energy Physics 7
Table 10The cross sections (in pb) for the relevant backgrounds (119882+119887(119887)119881119882+119888(119888)119881 and119882+119895119881 where119881 = photon jet and119885 boson) with119901119879cuts on the jets at the center of mass energyradic119904 = 13TeV
Background 119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119882+119887120574 + 119883 237 times 10
minus3362 times 10
minus4617 times 10
minus5699 times 10
minus6
119901119901 rarr 119882+119888120574 + 119883 415 times 10
0459 times 10
minus1625 times 10
minus2621 times 10
minus3
119901119901 rarr 119882+119895120574 + 119883 263 times 10
1430 times 10
0733 times 10
minus1127 times 10
minus1
119901119901 rarr 119882+119887(119887)119895 + 119883 726 times 10
1302 times 10
1611 times 10
0974 times 10
minus1
119901119901 rarr 119882+119888(119888)119895 + 119883 598 times 10
2965 times 10
1179 times 10
1242 times 10
0
119901119901 rarr 119882+119895119895 + 119883 731 times 10
3778 times 10
2161 times 10
2258 times 10
1
119901119901 rarr 119882+119887119885 + 119883 626 times 10
minus4399 times 10
minus4193 times 10
minus4471 times 10
minus5
119901119901 rarr 119882+119888119885 + 119883 529 times 10
minus1340 times 10
minus1166 times 10
minus1415 times 10
minus2
119901119901 rarr 119882+119895119885 + 119883 859 times 10
0483 times 10
0249 times 10
0791 times 10
minus1
500 600 700 800 900 100010minus2
10minus1
100
101
102
103
t998400 rarr tZ
t998400 rarr t120574
t998400 rarr tg
Mt998400 (GeV)
Lin
t(fb
minus1)
Figure 5 Integrated luminosity required to reach 3120590 significancefor the signal of 1199051015840 anomalous interactions for parametrization PI atthe LHC withradic119904 = 13TeV
102
103
104
500 600 700 800 900 1000
t998400 rarr tZ
t998400 rarr t120574
t998400 rarr tg
Mt998400 (GeV)
Lin
t(fb
minus1)
Figure 6 The same as Figure 5 but for parametrization PII
500 600 700 800 900 100010minus2
10minus1
100
101
102
103
t998400 rarr tZ
t998400 rarr t120574
t998400 rarr tg
Mt998400 (GeV)
Lin
t(fb
minus1)
Figure 7 The same as Figure 5 but for parametrization PIII
detector parametersThis fast simulation includes the impor-tant detector effects such as tracking smearing effects of thecalorimeters resolution and tag efficiencies The EXROOT-ANALYSIS package [31] is used for the simulated events andthe output is analyzed and histogrammed with the ROOT[32] macros We consider jets (up to five) leptons (electronsor muons) photons and missing transverse momentumwithin the simulated events for the 119905120574 119905119895 and 119905119885 eventsgeneration The typical kinematical distributions are shownin Figures 9-10
In the analysis the signal (with 120581Λ = 02TeVminus1 and1198981199051015840 = 700GeV) and the corresponding background (119882119895119881)
are taken into accountThe 119904-channel contribution to the sig-nal process appears as a resonance around the 1199051015840mass value inthe reconstructed invariant mass 119898rec
1199051015840 The reconstructed
mass distribution for the 1199051015840 signal (reconstructed from a topquark and a vector boson) is shown in Figure 11
Similar to the single top processes the top quark in thefinal state is reconstructed from a leading jet (commonly 119887jet)and a119882 boson (which can be reconstructed from its leptonicor hadronic decay) For the 119905120574 production we require
8 Advances in High Energy Physics
500 600 700 800 900 1000
Mt998400 (GeV)
01
02
03
04
05120581Λ
(TeV
minus1 )
t998400 rarr WbZ
t998400 rarr Wb120574
t998400 rarr Wbg
Figure 8The contour plot of anomalous coupling and mass of newheavy quark 1199051015840 for the dynamical parametrization explained in thetext with a significance of 3120590 atradic119904 = 13TeV and 119871 int = 100fb
minus1
50 100 150 200 250 300 350 400
Entr
ies
0
2000
4000
6000
8000
10000
12000
14000
16000
PhotonJet 1
Jet 2Jet 3
pT (GeV)
Figure 9 Transverse momentum distributions of leading jet (Jet 1)and other jets (Jet 2 and Jet 3) and photon for signal (119905120574 production)after detector simulation
systematically the large transverse momentum of photon(119901120574119879gt 100GeV) minimum jet transverse momentum (119901119895
119879gt
20GeV) and the pseudorapidity range (|120578119895120574| lt 25) inaddition to the requirements on mass reconstruction of119882-boson and top quark The large 119901120574
119879and the requirement of
single 119887-tagging allow a better separation of the signal (for 119905120574channel) from the background Other channels for 119905119892 and 119905119885productions are more challenging due to a large number ofjets which require additional discriminators such as angularandor total transverse energy variables However in orderto get rid of the backgrounds from 119882119905 and 119905119905 production
Entr
ies
50 100 150 200 250 300 350 4000
5000
10000
15000
20000
25000
PhotonJet 1
Jet 2Jet 3
pT (GeV)
Figure 10 Transverse momentum distributions of leading jet (Jet1) and other jets (Jet 2 and Jet 3) and photon for background (119882119895120574production)
500 600 700 800 900 1000
40
60
80
100
120
BackgroundSignal
Mrect998400
(GeV)
Even
ts10
GeV
Figure 11The reconstructedmass distributions for background andsignal (119905120574) with119898
1199051015840 = 700GeV and 120581Λ = 015TeVminus1
(for a similar framework the production cross sections areabout 25 pb and 340 pb resp) one can consider the channel3119897 + 119887jet + MET for a distinctive signal from the 1199051015840 rarr 119905119885An analysis of the investigation of single top production withsimilar backgrounds at the LHC can be found in [33ndash35]
42 Analysis of the Process 119901119901 rarr 119887119881 + 119883 (119881 = 119892 119885 120574) for1198871015840 Signal The signal process 119901119901 rarr 119887119881 + 119883 (119881 = 119892 119885 120574)includes the new heavy quark 1198871015840 exchange in both the 119904-channel and the 119905-channel The 119904-channel contributes to thesignal process as resonance around the 1198871015840mass value in the 119887119881invariantmass while the 119905-channel contributes to the nonres-onant behaviour For this process we consider the leptonicdecay of 119885 boson In the analyses we consider the 1198871015840 signalto be 119887jet + 120574 119887jet + 119895 and 119887jet + dilepton
Advances in High Energy Physics 9
Table 11 The cross sections (in pb) for 1198871015840 signal in different decay channel for parametrization PI with 119901119879cuts on the jets and photon and
|120578119895120574| lt 25 at the center of mass energyradic119904 = 13TeV
SignalMass (GeV)
PI119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887120574 + 119883
500 564 times 10minus2
562 times 10minus2
549 times 10minus2
395 times 10minus2
600 396 times 10minus2
396 times 10minus2
390 times 10minus2
333 times 10minus2
700 287 times 10minus2
287 times 10minus2
286 times 10minus2
259 times 10minus2
800 212 times 10minus2
213 times 10minus2
212 times 10minus2
199 times 10minus2
900 160 times 10minus2
160 times 10minus2
160 times 10minus2
153 times 10minus2
1000 122 times 10minus2
122 times 10minus2
122 times 10minus2
119 times 10minus2
119901119901 rarr 119887119892 + 119883
500 813 times 100
813 times 100
793 times 100
596 times 100
600 559 times 100
559 times 100
553 times 100
488 times 100
700 398 times 100
398 times 100
396 times 100
373 times 100
800 291 times 100
291 times 100
290 times 100
281 times 100
900 216 times 100
216 times 100
216 times 100
214 times 100
1000 164 times 100
163 times 100
163 times 100
162 times 100
119901119901 rarr 119887119885 + 119883
500 787 times 10minus1
781 times 10minus1
750 times 10minus1
479 times 10minus1
600 548 times 10minus1
548 times 10minus1
531 times 10minus1
427 times 10minus1
700 395 times 10minus1
394 times 10minus1
386 times 10minus1
339 times 10minus1
800 292 times 10minus1
291 times 10minus1
286 times 10minus1
261 times 10minus1
900 218 times 10minus1
218 times 10minus1
215 times 10minus1
202 times 10minus1
1000 166 times 10minus1
166 times 10minus1
164 times 10minus1
156 times 10minus1
We have obtained the cross sections by using the pseu-dorapidity cuts |120578
119895120574| lt 25 and transverse momentum cuts
119901119895120574
119879gt 20ndash200GeV for jets and photon in Table 11 (Tables
12 and 13) for PI (PII PIII) parametrizations respectivelyInvariantmass distribution of the 119887119881 (where119881 = 120574 119892 and119885)system is shown in Figure 12 for PI parametrization of thesignal with 120581Λ = 02TeVminus1 and 119898
1198871015840 = 700GeV at the
center of mass energy radic119904 = 13TeV It appears from sig-nal significance calculation that the optimized transversemomentum cut is 119901
119879gt 200GeV for 1198871015840 analyses
The backgrounds for the final state 119887(119887)119881 (where 119881 equiv
photon jet and 119885 boson) are given in Table 14 We apply thefollowing cuts to the final state photon and jets as |120578
119895120574| lt 25
and 119901119895120574119879gt 20ndash200GeV It can be noted that the background
cross section decreases as the119901119879cuts increaseWe assume the
efficiency for 119887-tagging to be 120576119887= 50and the rejection ratios
to be 10 for 119888 (119888) quark jets and 1 for light quark jetsIn order to reach 3120590 significance for the signal of 1198871015840
anomalous interactions the required integrated luminosityis shown in Figures 13ndash15 for parametrizations PI PII andPIII at the LHC with radic119904 = 13TeV The channel 1198871015840 rarr 119887120574
requires more integrated luminosity than the other channelsBy requiring the signal significance 119878119878 = 3 the contour plotsof 120581Λ and mass of 1198871015840 quark are presented in Figure 16 Theresults show that one can discover the 1198871015840 quark anomalouscouplings down to 01 in the 119887119892 channel for119898
1198871015840 = 500GeV
500 600 700 800 900 100010minus6
10minus5
10minus4
10minus3
10minus2
10minus1
100
d120590d
mbV
(pb
GeV
)
MbV (GeV)
pp rarr bg + X
pprarr bZ + X
pprarr b120574 + X
Figure 12 Invariant mass distribution of the 119887119881 (where 119881 = 120574 119892and 119885) system is shown in Figure 5 for PI parametrization of thesignal with 120581Λ = 02TeVminus1 and 119898
1198871015840 = 700GeV at the center of
mass energyradic119904 = 13TeV
421 Simulation for 1198871015840 Signal In the simulation we havegenerated 119887119881 (where 119881 = 120574 119892 and 119885) events for each sub-process and these events are simulated using generic detector
10 Advances in High Energy Physics
Table 12 The same as Table 11 but for parametrization PII
SignalMass (GeV)
PII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887120574 + 119883
500 518 times 10minus3
526 times 10minus3
504 times 10minus3
354 times 10minus3
600 338 times 10minus3
337 times 10minus3
336 times 10minus3
277 times 10minus3
700 232 times 10minus3
231 times 10minus3
230 times 10minus3
205 times 10minus3
800 171 times 10minus3
163 times 10minus3
164 times 10minus3
150 times 10minus3
900 117 times 10minus3
116 times 10minus3
117 times 10minus3
111 times 10minus3
1000 860 times 10minus4
858 times 10minus4
855 times 10minus4
824 times 10minus4
119901119901 rarr 119887119892 + 119883
500 740 times 10minus1
739 times 10minus1
721 times 10minus1
516 times 10minus1
600 483 times 10minus1
480 times 10minus1
481 times 10minus1
398 times 10minus1
700 322 times 10minus1
322 times 10minus1
320 times 10minus1
289 times 10minus1
800 224 times 10minus1
221 times 10minus1
221 times 10minus1
204 times 10minus1
900 15 times 10minus1
158 times 10minus1
158 times 10minus1
149 times 10minus1
1000 114 times 10minus1
114 times 10minus1
113 times 10minus1
110 times 10minus1
119901119901 rarr 119887119885 + 119883
500 689 times 10minus2
685 times 10minus2
645 times 10minus2
423 times 10minus2
600 452 times 10minus2
451 times 10minus2
434 times 10minus2
353 times 10minus2
700 312 times 10minus2
311 times 10minus2
305 times 10minus2
265 times 10minus2
800 219 times 10minus2
218 times 10minus2
215 times 10minus2
195 times 10minus2
900 156 times 10minus2
156 times 10minus2
155 times 10minus2
144 times 10minus2
1000 114 times 10minus2
113 times 10minus2
113 times 10minus2
107 times 10minus2
Table 13 The same as Table 11 but for parametrization PIII
SignalMass (GeV)
PIII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887120574 + 119883
500 131 times 10minus2
1314 times 10minus2
1275 times 10minus2
892 times 10minus2
600 859 times 10minus2
858 times 10minus2
844 times 10minus2
703 times 10minus2
700 582 times 10minus2
582 times 10minus2
577 times 10minus2
517 times 10minus2
800 407 times 10minus2
407 times 10minus2
406 times 10minus2
377 times 10minus2
900 292 times 10minus2
292 times 10minus2
291 times 10minus2
277 times 10minus2
1000 214 times 10minus2
213 times 10minus2
213 times 10minus2
206 times 10minus2
119901119901 rarr 119887119892 + 119883
500 1904 times 100
1896 times 100
1843 times 100
1286 times 100
600 1219 times 100
1213 times 100
1193 times 100
992 times 100
700 808 times 100
807 times 100
802 times 100
717 times 100
800 557 times 100
557 times 100
555 times 100
515 times 100
900 394 times 100
394 times 100
394 times 100
374 times 100
1000 285 times 100
285 times 100
285 times 100
274 times 100
119901119901 rarr 119887119885 + 119883
500 176 times 100
175 times 100
165 times 100
105 times 100
600 115 times 100
114 times 100
111 times 100
880 times 10minus1
700 783 times 10minus1
780 times 10minus1
760 times 10minus1
661 times 10minus1
800 547 times 10minus1
541 times 10minus1
531 times 10minus1
480 times 10minus1
900 392 times 10minus1
390 times 10minus1
382 times 10minus1
360 times 10minus1
1000 286 times 10minus1
282 times 10minus1
280 times 10minus1
262 times 10minus1
Advances in High Energy Physics 11
Table 14 The cross sections (in pb) for the backgrounds (119887(119887)119881 119888(119888)119881 and 119895119881 where119881 = photon jet and 119885 boson) with 119901119879cuts on the jets
and photon at the center of mass energy radic119904 = 13TeV
Background 119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887(119887)120574 + 119883 299 times 103
135 times 102
904 times 100
402 times 10minus1
119901119901 rarr 119888(119888)120574 + 119883 187 times 104
815 times 102
540 times 101
243 times 100
119901119901 rarr 119895120574 + 119883 543 times 104
327 times 103
338 times 102
285 times 101
119901119901 rarr 119887(119887)119895 + 119883 783 times 106
305 times 105
192 times 104
893 times 102
119901119901 rarr 119888(119888)119895 + 119883 122 times 107
455 times 105
289 times 104
135 times 103
119901119901 rarr 119895119895 + 119883 243 times 108
854 times 106
544 times 105
280 times 104
119901119901 rarr 119887(119887)119885 + 119883 502 times 102
135 times 102
225 times 101
156 times 100
119901119901 rarr 119888(119888)119885 + 119883 596 times 102
158 times 102
264 times 101
183 times 100
119901119901 rarr 119895119885 + 119883 800 times 103
208 times 103
408 times 102
412 times 101
500 600 700 800 900 1000
Mb998400 (GeV)
10minus1
100
101
102
103
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Figure 13 Integrated luminosity required to reach 3120590 significancefor the signal of 1198871015840 anomalous interactions for parametrization PI atthe LHC withradic119904 = 13TeV
500 600 700 800 900 1000
Mb998400 (GeV)
104
101
102
103
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Figure 14 The same as Figure 13 but for parametrization PII
500 600 700 800 900 100010minus1
100
101
102
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Mb998400 (GeV)
Figure 15 The same as Figure 13 but for parametrization PIII
parameters to include detector effects such as tracking tag-ging efficiencies and smearing effects After the simulationthe typical kinematical distributions are shown in Figures 17-18
In the analysis the signal (with 120581Λ = 03TeVminus1 and1198981198871015840 = 700GeV) and the corresponding background are
taken into account The invariant mass of the new heavyquark 1198871015840 can be reconstructed from a 119887jet and a neutral gaugeboson (where the 119885 boson can also be reconstructed fromits dilepton or hadronic decay) For the 119887120574 production werequire a large 119901120574
119879(gt100GeV) for photon and large 119901119895
119879
(gt100GeV) for jet and pseudorapidity |120578119895120574| (lt25) For the 119887120574signal channel the invariantmass distributions for signal andbackground events are shown in Figure 19The large 119901119895120574
119879and
the requirement of single 119887-tagging allow a better separationof the signal (for 119887120574 channel) from the background and thenwe find a precise limit for the anomalous coupling in thischannel For the 119887119892 and 119887119885 production we require two high119901119879jets (one 119887-jet) and a high 119901
119879jet in addition to the
reconstructed mass 119898rec119885 respectively The main character of
12 Advances in High Energy Physics
500 600 700 800 900 100001
02
03
04
05120581Λ
(TeV
minus1 )
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Mb998400 (GeV)
Figure 16The contour plot of anomalous coupling andmass of newheavy quark 1198871015840 for the dynamical parametrization explained in thetext with a significance of 3120590 atradic119904 = 13TeV and 119871 int = 100fb
minus1
50 100 150 200 250 300 350 400
Entr
ies
0
2000
4000
6000
8000
10000
PhotonJet 1
pT (GeV)
Figure 17 Transverse momentum distributions of leading jet andphoton (119887120574 production) for signal after detector simulation
the signal is the high 119901119895119879andor 119901120574
119879and single 119887-tagged jet
We calculate the signal and background events in the range|119898
rec1198871015840 (GeV) minus 700GeV| lt 50GeV and we find a similar
significance as shown in Figure 16
5 Conclusion
The new heavy quarks of up-type and down-type can be pro-duced with large numbers at the LHC if they have the anoma-lous couplings (via flavor changing neutral current) thatwell dominate over the charged current interactions The
Entr
ies
50 100 150 200 250 300 350 4000
2000
4000
6000
8000
10000
12000
PhotonJet 1
pT (GeV)
Figure 18 Transverse momentum distributions of leading jet andphoton (119895120574 production) for background at the given conditionsmentioned in the text
500 550 600 650 700 750 800 850 900 950 10000
500
1000
1500
2000
2500
3000
BackgroundSignal
Mrecb998400
(GeV)
Even
ts10
GeV
Figure 19The reconstructedmass distributions for background andsignal (119887120574) with119898
1198871015840 = 700GeV and 120581Λ = 03TeVminus1
single production of new heavy quarks can be achievedthrough the anomalous interactions at the LHC with radic119904 =13TeV The anomalous vertices could appear significantly atleading order processes due to the possibility of new heavyquarks From the results of signal significance calculationsfor 1199051015840 (1198871015840) anomalous productions the sensitivity to theanomalous couplings 120581119905
1015840
Λ (1205811198871015840
Λ) can be reached down to010 TeVminus1 (015 TeVminus1) in the lepton + 119887jet + jet +MET (119887jet +jet) channel at radic119904 = 13TeV assuming a dynamical para-metrization for the anomalous couplings and the mass of 750GeV for the new heavy quarks The observability limits onthe anomalous couplings obtained after the simulation arecomparable with the partonic level analysis in the photon and119885 boson associated channels whereas the productions 119905119892 and119887119892 are less comparable due to the fast simulation method In
Advances in High Energy Physics 13
any case the single 119887 tagging will play an important role inprobing new heavy quarks and reducing the background
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgment
This work was supported in part by Turkish Atomic EnergyAuthority (TAEA) under Project Grant no 2011TAEKCERN-A5H2P101-19
References
[1] H J He N Polonsky and S F Su ldquoExtra families Higgs spec-trum and oblique correctionsrdquo Physical Review D vol 64 no5 Article ID 053004 11 pages 2001
[2] B Holdom W S Hou T Hurth M L Mangano S Sultansoyand G Unel ldquoFour statements about the fourth generationrdquoPMC Physics A vol 3 article 4 2009
[3] A Atre M Carena T Han and J Santiago ldquoHeavy quarksabove the top at the Tevatronrdquo Physical ReviewD vol 79 ArticleID 054018 2009
[4] A Atre G Azuelos M Carena et al ldquoModel-independentsearches for new quarks at the LHCrdquo Journal of High EnergyPhysics vol 2011 no 8 article 080 2011
[5] N Chen and H J He ldquoLHC signatures of two-Higgs-doubletswith fourth familyrdquo Journal of High Energy Physics vol 2012article 062 2012
[6] M S Chanowitz ldquoElectroweak constraints on the fourth gener-ation at two loop orderrdquo Physical Review D vol 88 Article ID015012 2013
[7] S Chakdar K Ghosh S Nandi and S K Rai ldquoCollider signa-tures of mirror fermions in the framework of a left-right mirrormodelrdquo Physical Review D vol 88 Article ID 095005 2013
[8] X F Wang C Du and H J He ldquoLHC Higgs signatures fromtopflavor seesaw mechanismrdquo Physics Letters B vol 723 no 4-5 pp 314ndash323 2013
[9] S Bar-Shalom M Geller S Nandi and A Soni ldquoTwo higgsdoublets a 4th generation and a 125GeV higgs a reviewrdquoAdvances in High Energy Physics vol 2013 Article ID 67297228 pages 2013
[10] H Fritzsch and D Holtmannspotter ldquoThe production of singlet-quarks at LEP and HERArdquo Physics Letters B vol 457 no 1ndash3pp 186ndash192 1999
[11] G Aad B Abbott J Abdallah et al ldquoSearch for down-typefourth generation quarks with the ATLAS detector in eventswith one lepton and hadronically decaying119882 bosonsrdquo PhysicalReview Letters vol 109 Article ID 032001 2012
[12] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoSearchfor pair produced fourth-generation up-type quarks in ppcollisions atradic119904 = 7 TeV with a lepton in the final staterdquo PhysicsLetters B vol 718 pp 307ndash328 2012
[13] G Aad B Abbott J Abdallah et al ldquoSearch for pair and singleproduction of new heavy quarks that decay to a Z boson and athird-generation quark in pp collisions at radic119904 = 8TeV with theATLAS detectorrdquo Journal of High Energy Physics vol 2014 no11 article 104 2014
[14] G Aad T Abajyan B Abbott et al ldquoSearch for pair productionof heavy top-like quarks decaying to a high-pTW boson and ab quark in the lepton plus jets final state at radic119904 = 7TeV with theATLAS detectorrdquo Physics Letters B vol 718 no 4ndash5 pp 1284ndash1302 2013
[15] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoSearchfor heavy top-like quark pair production in the dilepton finalstate in pp collisions at radic119904 = 7TeVrdquo Physics Letters B vol 716no 1 pp 103ndash121 2012
[16] G Aad B Abbott J Abdallah et al ldquoSearch for heavy vector-like quarks coupling to light quarks in protonndashproton collisionsat radic119904 = 7 Tev with the ATLAS detectorrdquo Physics Letters B vol712 no 1-2 pp 22ndash39 2012
[17] G Aad T Abajyan B Abbott et al ldquoSearch for a heavy top-quark partner in final states with two leptons with the ATLASdetector at the LHCrdquo Journal of High Energy Physics vol 2012article 94 2012
[18] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoCom-bined search for the quarks of a sequential fourth generationrdquoPhysical Review D vol 86 no 11 Article ID 112003 20 pages2012
[19] R Ciftci ldquoAnomalous single production of the fourth gener-ation quarks at the CERN LHCrdquo Physical Review D vol 78Article ID 075018 2008
[20] I T Cakır H D Yıldız O Cakır and G Unel ldquoAnomalousresonant production of the fourth-family up-type quarks at theLHCrdquo Physical Review D vol 80 Article ID 095009 2009
[21] M Sahin S Sultansoy and S Turkoz ldquoSearching for the fourthfamily quarks through anomalous decaysrdquo Physical Review Dvol 82 no 5 Article ID 051503 2010
[22] M Bobrowski A Lenz J Riedl and J Rohrwild ldquoHow muchspace is left for a new family of fermionsrdquo Physical Review Dvol 79 no 11 Article ID 113006 15 pages 2009
[23] G Eilam B Melic and J Trampetic ldquo119862119875 violation and thefourth generationrdquo Physical Review D vol 80 no 11 Article ID116003 2009
[24] O Cobanoglu E Ozcan S Sultansoy and G Unel ldquoOPUCEMa library with error checkingmechanism for computing obliqueparametersrdquo Computer Physics Communications vol 182 no 8pp 1732ndash1743 2011
[25] T Han and J L Hewett ldquoTop-charm associated production inhigh energy 119890+119890minus collisionsrdquo Physical Review D vol 60 ArticleID 074015 1999
[26] A Belyaev N D Christensen and A Pukhov ldquoCalcHEP 34for collider physics within and beyond the standard modelrdquoComputer Physics Communications vol 184 no 7 pp 1729ndash1769 2013
[27] J Pumplin D Robert Stump J Huston H-L Lai P Nadolskyand W-K Tung ldquoNew generation of Parton distributions withuncertainties from global QCD analysisrdquo Journal of High EnergyPhysics vol 2002 article 012 2002
[28] G L Bayatian S Chatrchyan G Hmayakyan et al ldquoCMSphysics technical design report volume II physics perfor-mancerdquo Journal of Physics G Nuclear and Particle Physics vol34 no 6 p 995 2007
[29] T Sjostrand S Mrenna and P Skands ldquoPYTHIA 64 physicsand manualrdquo Journal of High Energy Physics vol 2006 no 5 p026 2006
[30] J Conway R Culbertson and R Demina Pretty Good Sim-ulation (PGS4) httpwwwphysicsucdavisedusimconwayresearchsoftwarepgspgs4-generalhtm
14 Advances in High Energy Physics
[31] EXROOTANALYSIS package for PGS4 data analysishttpmadgraphhepuiuceduDownloadsExRootAnalysis
[32] R Brun et al An object oriented data analysis framework(ROOT) httpsrootcernchdrupal
[33] F del Aguila and J A Aguilar-Saavedra ldquoMultilepton produc-tion via top flavour-changing neutral couplings at the CERNLHCrdquo Nuclear Physics B vol 576 pp 56ndash84 2000
[34] T Han M Hosch K Whisnant B-L Young and X ZhangldquoSingle top quark production via FCNC couplings at hadroncollidersrdquo Physical Review D vol 58 Article ID 073008 1998
[35] T Stelzer Z Sullivan and S Willenbrock ldquoSingle-top-quarkproduction at hadron collidersrdquoPhysical ReviewD vol 58 no 9Article ID 094021 11 pages 1998
background Any observations of the invariant mass peak inthe range of 500ndash1000GeV and excess in the events with thefinal states originating from119882119887119881 and 119887119881 can be interpretedas the signal for the new heavy quarks 1199051015840 and 1198871015840 via theanomalous interactions
2 New Heavy Quarks Anomalous Interactions
A general theory that includes the standard model (SM) asits low energy limit can be written as an expansion seriesin powers of Λminus1 with operators obeying the required sym-metries The dimension six gauge invariant operators can bebuilt from the SM fields and they can induce dimension fiveoperators after spontaneous symmetry breaking The coef-ficients of the dimension five terms are related to those ofdimension six operators and they can lead to sizable effects inthe heavy quark associated production in high energy col-lisions [25] For our study the effective Lagrangian withdimension five terms for the anomalous interactions amongthe new heavy quarks (1198761015840 equiv 1199051015840 or 1198871015840) ordinary quarks 119902 andthe gauge bosons 119881 = 120574 119885 119892 can be written explicitly
119871 = sum
119902119894=119906119888119905
120581119902119894
120574
Λ119876119902119894
1198921198901199051015840
120590120583]119902119894119865120583]+ sum
119902119894=119906119888119905
120581119902119894
119911
2Λ1198921199111199051015840
120590120583]119902119894119885120583]
+ sum
119902119894=119906119888119905
120581119902119894
119892
2Λ1198921199041199051015840
120590120583]120582119886119902119894119866
120583]119886+ sum
119902119894=119889119904119887
120581119902119894
120574
Λ119876119902119894
1198921198901198871015840
120590120583]119902119894119865120583]
+ sum
119902119894=119889119904119887
120581119902119894
119911
2Λ1198921199111198871015840
120590120583]119902119894119885120583]+ sum
119902119894=119889119904119887
120581119902119894
119892
2Λ1198921199041198871015840
120590120583]120582119886119902119894119866
120583]119886
+ hc(1)
where 119865120583] 119885120583] and 119866120583] are the field strength tensors of thegauge bosons 120590
120583] = 119894(120574120583120574] minus 120574]120574120583)2 120582119886 are the Gell-Mannmatrices119876
119902is the electric charge of the quark (119902) 119892
119890 119892119885 and
119892119904are the electromagnetic neutral weak and strong coupling
constants respectively 119892119885= 119892119890 cos 120579
119908sin 120579119908 where 120579
119908is
the weak mixing angle 120581120574is the anomalous coupling with
photon 120581119911is for the 119885 boson and 120581
119892is the coupling with
gluon Finally Λ is the cutoff scale for the new interactions
3 Decay Widths and Branchings
For the decay channels 1198761015840 rarr 119881119902 where 119881 equiv 120574 119885 and 119892 weuse the effective Lagrangian to calculate the anomalous decaywidths
Γ (1198761015840997888rarr 119892119902) =
2
3(120581119902
119892
Λ)
2
1205721199041198983
11987610158401205820
Γ (1198761015840997888rarr 120574119902) =
1
2(120581119902
120574
Λ)
2
1205721198901198762
1199021198983
11987610158401205820
Γ (1198761015840997888rarr 119885119902) =
1
16(120581119902
119885
Λ)
21205721198901198983
1198761015840
sin2120579119882cos2120579119882
120582119885radic120582119903
(2)
Table 1 Branching ratios () and decay width of the new heavyquark (1199051015840) with only anomalous interactions for PI parametrizationand 120581Λ = 01 TeVminus1
The anomalous decay widths in different channels areproportional to Λminus2 and they are assumed to be dominantfor 120581Λ gt 01TeVminus1 over the charged current channels Inthis case if we take all the anomalous coupling equal then thebranching ratios will be nearly independent of 120581Λ We haveused three parametrization sets entitled PI PII and PIII Forthe PI parametrization we assume the constant value 120581
119894Λ =
01TeVminus1 and PII has the parameters 120581119894Λ = 01120582
4minus119894 TeVminus1with 120582 = 05 For PIII we take the couplings 120581
119894Λ =
051205824minus119894 TeVminus1 with the same value of 120582 The index 119894 is the
generation numberTables 1 and 2 present the decay width and branching
ratios of the new heavy quark 1199051015840 through anomalous inter-actions for the parametrization PI PII and PIII respectivelyTaking the anomalous coupling 120581Λ = 01TeVminus1 we calculatethe 1199051015840 decay width Γ = 065GeV and 190GeV for 119898
1199051015840 =
700GeV and 1000GeV respectivelyThe branching into 1199051015840 rarr119902119892 channel is the largest and branching into 1199051015840 rarr 119902120574
channel is the smallest for equal anomalous couplings withthe parametrization PI On the other hand PII and PIIIparametrization give higher branching ratios into 119905119881 (119881 =
119892 119885 120574) than 119902119881 (119902 = 119906 119888) channels due to 1205824minus119894 factor in theparametrization
For the new heavy quark 1198871015840 the decay width and branch-ing ratios are presented in Tables 3 and 4 for the parametriza-tions PI PII and PIII respectively We calculate the 1198871015840 decaywidth by taking the anomalous couplings 120581Λ = 01TeVminus1Γ = 068GeV and 192GeV for119898
1198871015840 = 700GeV and 1000GeV
respectively The branching for 1198871015840 rarr 119902119892 is the largest (30)and it is the smallest for 1198871015840 rarr 119902120574 (02) channel for equalanomalous couplings with the parametrization PI For PII
Advances in High Energy Physics 3
Table 2 The same as Table 1 but for PII (PIII) parametrization
Figure 1 Diagrams for the subprocess 119892119902 rarr 119881119876 with anomalous vertices 1198761015840119902119881 and 1198761015840119876119881 (where 1198761015840 can be the new heavy quark 1198871015840 or 1199051015840depending on the type of light (119902) or heavy (119876 equiv 119905 119887) quarks resp)
Table 3 Branching ratios () and decay width of the new heavyquark (1198871015840) with only anomalous interactions for PI parametrizationand 120581Λ = 01 TeVminus1
and PIII parametrization the branching ratios into 119887119881 (119881 =
119892 119885 120574) are larger than 119902119881 (119902 = 119889 119904) channels The 1199051015840 and1198871015840 decay widths are about the same values for PII and PIIIparametrization
4 The Cross Sections
In order to study the new heavy quark productions at theLHC we have used effective anomalous interaction verticesand implemented these vertices into the CalcHEP package[26] In all of the numerical calculations the parton dis-tribution functions are set to the CTEQ6L parametrization[27] The new heavy quarks can be produced through theiranomalous couplings to the ordinary quarks and neutralvector bosons as shown in Figure 1
Total cross sections for the productions of new heavyquarks 1199051015840 and 119887
1015840 are given in Tables 5 and 6 for theparametrizations PI PII and PIII at the center of massenergy of 8 TeV and 13 TeV For an illustration taking themass of new heavy quarks as 700GeV the cross section of1199051015840(1198871015840) production is calculated as 850 pb (1003 pb) for the
parametrization PIII at radic119904 = 13TeV It can be seen fromTables 5 and 6 that the cross section decreases while the
PIIIPIPII
10minus1
100
101
102
500 600 700 800 900 1000
120590(p
b)
Mt998400 (GeV)
Figure 2The cross section for the process 119901119901 rarr 119905119881+119883 dependingon the mass for parameter sets PI PII and PIII at the center of massenergyradic119904 = 13TeV
mass of the new heavy quark increases The cross section for1199051015840 production is larger than the 1198871015840 production with a factor of12ndash18 (07ndash10) for PI (PII and PIII) parametrization depend-ing on the consideredmass range atradic119904 = 13TeVThe generalbehaviour of the production cross sections depending on themass of new heavy quarks is presented in Figures 2 and 3 fordifferent parametrizations
41 Analysis of the Process 119901119901 rarr 119882+119887119881+119883 (119881 = 119892 119885 120574) for
1199051015840 Signal The signal process 119901119901 rarr 119882
includes the 1199051015840 exchange in both the 119904-channel and 119905-channelThe 119904-channel contribution to the signal process wouldappear itself as resonance around the 1199051015840 mass value in the119882119887119881 invariant mass The 119905-channel gives the nonresonant
4 Advances in High Energy Physics
Table 4 The same as Table 3 but for PII (PIII) parametrization
Table 5The cross sections (in pb) of new heavy quark 1199051015840 production without cuts for PI PII and PIII parametrizations at the center of massenergy 13TeV (8TeV) respectively
Mass (GeV) PI PII PIIIradic119904 = 13 TeV (8 TeV) radic119904 = 13 TeV (8 TeV) radic119904 = 13 TeV (8 TeV)
Figure 3The cross section for the process119901119901 rarr 119887119881+119883 dependingon the new heavy quark mass for parameter sets PI PII and PII atthe center of mass energyradic119904 = 13TeV
contribution We consider that the 119882 boson decays intolepton + missing transverse momentum with the branchingratio of 21 and 119885 boson decays into dilepton with thebranching ratio of 67 In our analyses we consider the 1199051015840signal in the 119897 + 119887jet + 120574 + MET 119897 + 119887jet + 119895 + MET and3119897 + 119887jet +MET channels where 119897 = 119890 120583 However if one takesthe hadronic119882 decay the signal will be enhanced by a factorof BR(119882 rarr hadrons)BR(119882 rarr 119897])
We have obtained the cross sections by using the cutspseudorapidity |120578
119895120574| lt 25 and transverse momentum 119901
119895120574
119879gt
20ndash200GeV for jets and photon in Table 7 (Tables 8 and 9)
500 600 700 800 900 100010minus6
10minus5
10minus4
10minus3
10minus2
10minus1
100
d120590d
mtV
(pb
GeV
)
MtV (GeV)
pp rarr tg + X
pp rarr tZ + X
pp rarr t120574 + X
Figure 4 Invariant mass distributions 119898119905119881
(where 119881 = 120574 119892 and119885) for PI parametrization of the signal with 120581Λ = 02TeVminus1 and1198981199051015840 = 700GeV at the center of mass energy radic119904 = 13TeV
for PI (PII PIII) parametrization respectively Invariantmassdistribution of the 119905119881 (where 119881 = 120574 119892 and 119885) system isshown in Figure 4 for PI parametrization of the signal with120581Λ = 02TeVminus1 and 119898
1199051015840 = 700GeV at the center of mass
energy radic119904 = 13TeV It appears from signal significance cal-culations that the optimized transverse momentum cut is119901119895120574
119879gt 100GeV for 1199051015840 analysesThe backgrounds for the final state119882+119887(119887)119881 (where 119881 equiv
photon jet and 119885 boson) are given in Table 10 We apply thefollowing cuts to the final state photon and jets as |120578
119895120574| lt 25
and 119901119895120574119879
gt 20ndash200GeV For the background cross section
Advances in High Energy Physics 5
Table 6The cross sections (in pb) of new heavy quark 1198871015840 production without cuts for PI PII and PIII parametrizations at the center of massenergy of 13TeV (8TeV) respectively
Mass (GeV) PI PII PIIIradic119904 = 13 TeV (8 TeV) radic119904 = 13 TeV (8 TeV) radic119904 = 13 TeV (8 TeV)
Table 7 The cross sections (in pb) for 1199051015840 signal in different decay channels for PI parametrization with 119901119879cuts on the jets and photon and
|120578119895120574| lt 25 at the center of mass energyradic119904 = 13TeV
SignalMass (GeV)
PI119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119882+119887120574 + 119883
500 289 times 10minus1
210 times 10minus1
124 times 10minus1
102 times 10minus4
600 243 times 10minus1
164 times 10minus1
119 times 10minus1
123 times 10minus2
700 168 times 10minus1
12 times 10minus1
112 times 10minus1
225 times 10minus2
800 130 times 10minus1
103 times 10minus1
753 times 10minus2
325 times 10minus2
900 102 times 10minus1
808 times 10minus2
696 times 10minus2
302 times 10minus2
1000 761 times 10minus2
635 times 10minus2
507 times 10minus2
294 times 10minus2
119901119901 rarr 119882+119887119892 + 119883
500 778 times 100
602 times 100
363 times 100
474 times 10minus3
600 630 times 100
518 times 100
313 times 100
258 times 10minus1
700 499 times 100
363 times 100
304 times 100
932 times 10minus1
800 401 times 100
345 times 100
276 times 100
991 times 10minus1
900 332 times 100
277 times 100
213 times 100
108 times 100
1000 258 times 100
227 times 100
188 times 100
101 times 100
119901119901 rarr 119882+119887119885+119883
500 796 times 10minus1
601 times 10minus1
301 times 10minus1
101 times 10minus4
600 479 times 10minus1
386 times 10minus1
245 times 10minus1
271 times 10minus3
700 399 times 10minus1
312 times 10minus1
239 times 10minus1
696 times 10minus2
800 331 times 10minus1
289 times 10minus1
209 times 10minus1
805 times 10minus2
900 273 times 10minus1
273 times 10minus1
191 times 10minus1
954 times 10minus2
1000 223 times 10minus1
202 times 10minus1
161 times 10minus1
910 times 10minus2
estimates we assume the efficiency for 119887-tagging to be 120576119887=
50 and the rejection ratios to be 10 for 119888 (119888) quark jets and1 for light quark jets since they are assumed to bemistaggedas 119887-jets
In order to find the discovery limits we use the statisticalsignificance [28] defined as
where 119878 and 119861 are the numbers of the signal and backgroundevents respectively In Figures 5ndash7 the integrated luminosityrequired to reach 3120590 significance for the signal of 1199051015840 anoma-lous interactions is shown for parametrizations PI PII andPIII at the LHC with radic119904 = 13 TeV It is seen from these
figures that the channel 1199051015840 rarr 119905119885 requires more integratedluminosity than the other channels By requiring the signalsignificance 119878119878 = 3 the contour plots of 120581Λ and mass of1199051015840 quark are presented in Figure 8 The results show that onecan discover the 1199051015840 quark anomalous couplings 120581Λ down to01 TeVminus1 in the 119905119892 channel for119898
1199051015840 = 750GeV
411 Simulation for 1199051015840 Signal In order to include detectoreffects in the simulation we have generated 119905119881 (where 119881 =
120574 119892 and 119885) signal events for each subprocess and they aremixed using the ldquoevent mixerrdquo script which can be foundwithin the CALCHEP package [26] For further decay andhadronization these events are passed to PYTHIA [29] andsimulated with the PGS4 program [30] using generic LHC
6 Advances in High Energy Physics
Table 8 The same as Table 7 but for parametrization PII
SignalMass (GeV)
PII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119882+119887120574 + 119883
500 678 times 10minus3
507 times 10minus3
345 times 10minus3
264 times 10minus7
600 657 times 10minus3
542 times 10minus3
347 times 10minus3
534 times 10minus4
700 502 times 10minus3
431 times 10minus3
304 times 10minus3
873 times 10minus4
800 391 times 10minus3
376 times 10minus3
256 times 10minus3
103 times 10minus3
900 303 times 10minus3
268 times 10minus3
211 times 10minus3
101 times 10minus3
1000 240 times 10minus3
243 times 10minus3
177 times 10minus3
998 times 10minus4
119901119901 rarr 119882+119887119892 + 119883
500 347 times 10minus1
268 times 10minus1
152 times 10minus1
530 times 10minus6
600 251 times 10minus1
212 times 10minus1
135 times 10minus1
201 times 10minus2
700 187 times 10minus1
16 times 10minus1
116 times 10minus1
342 times 10minus2
800 146 times 10minus1
125 times 10minus1
939 times 10minus2
403 times 10minus2
900 112 times 10minus1
108 times 10minus1
780 times 10minus2
386 times 10minus2
1000 935 times 10minus2
837 times 10minus2
662 times 10minus2
368 times 10minus2
119901119901 rarr 119882+119887119885+119883
500 210 times 10minus2
177 times 10minus2
116 times 10minus2
264 times 10minus7
600 195 times 10minus2
175 times 10minus2
114 times 10minus2
134 times 10minus3
700 173 times 10minus2
143 times 10minus2
100 times 10minus2
29 times 10minus3
800 134 times 10minus2
119 times 10minus2
889 times 10minus3
342 times 10minus3
900 106 times 10minus2
955 times 10minus3
763 times 10minus3
337 times 10minus3
1000 809 times 10minus3
758 times 10minus3
631 times 10minus3
323 times 10minus3
Table 9 The same as Table 7 but for parametrization PIII
SignalMass (GeV)
PIII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119882+119887120574 + 119883
500 260 times 10minus1
278 times 10minus1
108 times 10minus1
159 times 10minus4
600 178 times 10minus1
161 times 10minus1
101 times 10minus1
142 times 10minus2
700 156 times 10minus1
135 times 10minus1
933 times 10minus2
272 times 10minus2
800 117 times 10minus1
106 times 10minus1
784 times 10minus2
332 times 10minus2
900 904 times 10minus2
842 times 10minus2
668 times 10minus2
325 times 10minus2
1000 760 times 10minus2
676 times 10minus2
516 times 10minus2
317 times 10minus2
119901119901 rarr 119882+119887119892 + 119883
500 839 times 100
649 times 100
386 times 100
465 times 10minus3
600 610 times 100
578 times 100
381 times 100
556 times 10minus1
700 539 times 100
464 times 100
341 times 100
970 times 10minus1
800 394 times 100
354 times 100
273 times 100
105 times 100
900 324 times 100
276 times 100
227 times 100
107 times 100
1000 233 times 100
229 times 100
184 times 100
998 times 10minus1
119901119901 rarr 119882+119887119885+119883
500 772 times 10minus1
101 times 100
217 times 10minus1
627 times 10minus4
600 624 times 10minus1
385 times 10minus1
292 times 10minus1
320 times 10minus2
700 500 times 10minus1
305 times 10minus1
286 times 10minus1
580 times 10minus2
800 378 times 10minus1
250 times 10minus1
242 times 10minus1
964 times 10minus2
900 304 times 10minus1
167 times 10minus1
206 times 10minus1
962 times 10minus2
1000 251 times 10minus1
129 times 10minus1
148 times 10minus1
961 times 10minus2
Advances in High Energy Physics 7
Table 10The cross sections (in pb) for the relevant backgrounds (119882+119887(119887)119881119882+119888(119888)119881 and119882+119895119881 where119881 = photon jet and119885 boson) with119901119879cuts on the jets at the center of mass energyradic119904 = 13TeV
Background 119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119882+119887120574 + 119883 237 times 10
minus3362 times 10
minus4617 times 10
minus5699 times 10
minus6
119901119901 rarr 119882+119888120574 + 119883 415 times 10
0459 times 10
minus1625 times 10
minus2621 times 10
minus3
119901119901 rarr 119882+119895120574 + 119883 263 times 10
1430 times 10
0733 times 10
minus1127 times 10
minus1
119901119901 rarr 119882+119887(119887)119895 + 119883 726 times 10
1302 times 10
1611 times 10
0974 times 10
minus1
119901119901 rarr 119882+119888(119888)119895 + 119883 598 times 10
2965 times 10
1179 times 10
1242 times 10
0
119901119901 rarr 119882+119895119895 + 119883 731 times 10
3778 times 10
2161 times 10
2258 times 10
1
119901119901 rarr 119882+119887119885 + 119883 626 times 10
minus4399 times 10
minus4193 times 10
minus4471 times 10
minus5
119901119901 rarr 119882+119888119885 + 119883 529 times 10
minus1340 times 10
minus1166 times 10
minus1415 times 10
minus2
119901119901 rarr 119882+119895119885 + 119883 859 times 10
0483 times 10
0249 times 10
0791 times 10
minus1
500 600 700 800 900 100010minus2
10minus1
100
101
102
103
t998400 rarr tZ
t998400 rarr t120574
t998400 rarr tg
Mt998400 (GeV)
Lin
t(fb
minus1)
Figure 5 Integrated luminosity required to reach 3120590 significancefor the signal of 1199051015840 anomalous interactions for parametrization PI atthe LHC withradic119904 = 13TeV
102
103
104
500 600 700 800 900 1000
t998400 rarr tZ
t998400 rarr t120574
t998400 rarr tg
Mt998400 (GeV)
Lin
t(fb
minus1)
Figure 6 The same as Figure 5 but for parametrization PII
500 600 700 800 900 100010minus2
10minus1
100
101
102
103
t998400 rarr tZ
t998400 rarr t120574
t998400 rarr tg
Mt998400 (GeV)
Lin
t(fb
minus1)
Figure 7 The same as Figure 5 but for parametrization PIII
detector parametersThis fast simulation includes the impor-tant detector effects such as tracking smearing effects of thecalorimeters resolution and tag efficiencies The EXROOT-ANALYSIS package [31] is used for the simulated events andthe output is analyzed and histogrammed with the ROOT[32] macros We consider jets (up to five) leptons (electronsor muons) photons and missing transverse momentumwithin the simulated events for the 119905120574 119905119895 and 119905119885 eventsgeneration The typical kinematical distributions are shownin Figures 9-10
In the analysis the signal (with 120581Λ = 02TeVminus1 and1198981199051015840 = 700GeV) and the corresponding background (119882119895119881)
are taken into accountThe 119904-channel contribution to the sig-nal process appears as a resonance around the 1199051015840mass value inthe reconstructed invariant mass 119898rec
1199051015840 The reconstructed
mass distribution for the 1199051015840 signal (reconstructed from a topquark and a vector boson) is shown in Figure 11
Similar to the single top processes the top quark in thefinal state is reconstructed from a leading jet (commonly 119887jet)and a119882 boson (which can be reconstructed from its leptonicor hadronic decay) For the 119905120574 production we require
8 Advances in High Energy Physics
500 600 700 800 900 1000
Mt998400 (GeV)
01
02
03
04
05120581Λ
(TeV
minus1 )
t998400 rarr WbZ
t998400 rarr Wb120574
t998400 rarr Wbg
Figure 8The contour plot of anomalous coupling and mass of newheavy quark 1199051015840 for the dynamical parametrization explained in thetext with a significance of 3120590 atradic119904 = 13TeV and 119871 int = 100fb
minus1
50 100 150 200 250 300 350 400
Entr
ies
0
2000
4000
6000
8000
10000
12000
14000
16000
PhotonJet 1
Jet 2Jet 3
pT (GeV)
Figure 9 Transverse momentum distributions of leading jet (Jet 1)and other jets (Jet 2 and Jet 3) and photon for signal (119905120574 production)after detector simulation
systematically the large transverse momentum of photon(119901120574119879gt 100GeV) minimum jet transverse momentum (119901119895
119879gt
20GeV) and the pseudorapidity range (|120578119895120574| lt 25) inaddition to the requirements on mass reconstruction of119882-boson and top quark The large 119901120574
119879and the requirement of
single 119887-tagging allow a better separation of the signal (for 119905120574channel) from the background Other channels for 119905119892 and 119905119885productions are more challenging due to a large number ofjets which require additional discriminators such as angularandor total transverse energy variables However in orderto get rid of the backgrounds from 119882119905 and 119905119905 production
Entr
ies
50 100 150 200 250 300 350 4000
5000
10000
15000
20000
25000
PhotonJet 1
Jet 2Jet 3
pT (GeV)
Figure 10 Transverse momentum distributions of leading jet (Jet1) and other jets (Jet 2 and Jet 3) and photon for background (119882119895120574production)
500 600 700 800 900 1000
40
60
80
100
120
BackgroundSignal
Mrect998400
(GeV)
Even
ts10
GeV
Figure 11The reconstructedmass distributions for background andsignal (119905120574) with119898
1199051015840 = 700GeV and 120581Λ = 015TeVminus1
(for a similar framework the production cross sections areabout 25 pb and 340 pb resp) one can consider the channel3119897 + 119887jet + MET for a distinctive signal from the 1199051015840 rarr 119905119885An analysis of the investigation of single top production withsimilar backgrounds at the LHC can be found in [33ndash35]
42 Analysis of the Process 119901119901 rarr 119887119881 + 119883 (119881 = 119892 119885 120574) for1198871015840 Signal The signal process 119901119901 rarr 119887119881 + 119883 (119881 = 119892 119885 120574)includes the new heavy quark 1198871015840 exchange in both the 119904-channel and the 119905-channel The 119904-channel contributes to thesignal process as resonance around the 1198871015840mass value in the 119887119881invariantmass while the 119905-channel contributes to the nonres-onant behaviour For this process we consider the leptonicdecay of 119885 boson In the analyses we consider the 1198871015840 signalto be 119887jet + 120574 119887jet + 119895 and 119887jet + dilepton
Advances in High Energy Physics 9
Table 11 The cross sections (in pb) for 1198871015840 signal in different decay channel for parametrization PI with 119901119879cuts on the jets and photon and
|120578119895120574| lt 25 at the center of mass energyradic119904 = 13TeV
SignalMass (GeV)
PI119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887120574 + 119883
500 564 times 10minus2
562 times 10minus2
549 times 10minus2
395 times 10minus2
600 396 times 10minus2
396 times 10minus2
390 times 10minus2
333 times 10minus2
700 287 times 10minus2
287 times 10minus2
286 times 10minus2
259 times 10minus2
800 212 times 10minus2
213 times 10minus2
212 times 10minus2
199 times 10minus2
900 160 times 10minus2
160 times 10minus2
160 times 10minus2
153 times 10minus2
1000 122 times 10minus2
122 times 10minus2
122 times 10minus2
119 times 10minus2
119901119901 rarr 119887119892 + 119883
500 813 times 100
813 times 100
793 times 100
596 times 100
600 559 times 100
559 times 100
553 times 100
488 times 100
700 398 times 100
398 times 100
396 times 100
373 times 100
800 291 times 100
291 times 100
290 times 100
281 times 100
900 216 times 100
216 times 100
216 times 100
214 times 100
1000 164 times 100
163 times 100
163 times 100
162 times 100
119901119901 rarr 119887119885 + 119883
500 787 times 10minus1
781 times 10minus1
750 times 10minus1
479 times 10minus1
600 548 times 10minus1
548 times 10minus1
531 times 10minus1
427 times 10minus1
700 395 times 10minus1
394 times 10minus1
386 times 10minus1
339 times 10minus1
800 292 times 10minus1
291 times 10minus1
286 times 10minus1
261 times 10minus1
900 218 times 10minus1
218 times 10minus1
215 times 10minus1
202 times 10minus1
1000 166 times 10minus1
166 times 10minus1
164 times 10minus1
156 times 10minus1
We have obtained the cross sections by using the pseu-dorapidity cuts |120578
119895120574| lt 25 and transverse momentum cuts
119901119895120574
119879gt 20ndash200GeV for jets and photon in Table 11 (Tables
12 and 13) for PI (PII PIII) parametrizations respectivelyInvariantmass distribution of the 119887119881 (where119881 = 120574 119892 and119885)system is shown in Figure 12 for PI parametrization of thesignal with 120581Λ = 02TeVminus1 and 119898
1198871015840 = 700GeV at the
center of mass energy radic119904 = 13TeV It appears from sig-nal significance calculation that the optimized transversemomentum cut is 119901
119879gt 200GeV for 1198871015840 analyses
The backgrounds for the final state 119887(119887)119881 (where 119881 equiv
photon jet and 119885 boson) are given in Table 14 We apply thefollowing cuts to the final state photon and jets as |120578
119895120574| lt 25
and 119901119895120574119879gt 20ndash200GeV It can be noted that the background
cross section decreases as the119901119879cuts increaseWe assume the
efficiency for 119887-tagging to be 120576119887= 50and the rejection ratios
to be 10 for 119888 (119888) quark jets and 1 for light quark jetsIn order to reach 3120590 significance for the signal of 1198871015840
anomalous interactions the required integrated luminosityis shown in Figures 13ndash15 for parametrizations PI PII andPIII at the LHC with radic119904 = 13TeV The channel 1198871015840 rarr 119887120574
requires more integrated luminosity than the other channelsBy requiring the signal significance 119878119878 = 3 the contour plotsof 120581Λ and mass of 1198871015840 quark are presented in Figure 16 Theresults show that one can discover the 1198871015840 quark anomalouscouplings down to 01 in the 119887119892 channel for119898
1198871015840 = 500GeV
500 600 700 800 900 100010minus6
10minus5
10minus4
10minus3
10minus2
10minus1
100
d120590d
mbV
(pb
GeV
)
MbV (GeV)
pp rarr bg + X
pprarr bZ + X
pprarr b120574 + X
Figure 12 Invariant mass distribution of the 119887119881 (where 119881 = 120574 119892and 119885) system is shown in Figure 5 for PI parametrization of thesignal with 120581Λ = 02TeVminus1 and 119898
1198871015840 = 700GeV at the center of
mass energyradic119904 = 13TeV
421 Simulation for 1198871015840 Signal In the simulation we havegenerated 119887119881 (where 119881 = 120574 119892 and 119885) events for each sub-process and these events are simulated using generic detector
10 Advances in High Energy Physics
Table 12 The same as Table 11 but for parametrization PII
SignalMass (GeV)
PII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887120574 + 119883
500 518 times 10minus3
526 times 10minus3
504 times 10minus3
354 times 10minus3
600 338 times 10minus3
337 times 10minus3
336 times 10minus3
277 times 10minus3
700 232 times 10minus3
231 times 10minus3
230 times 10minus3
205 times 10minus3
800 171 times 10minus3
163 times 10minus3
164 times 10minus3
150 times 10minus3
900 117 times 10minus3
116 times 10minus3
117 times 10minus3
111 times 10minus3
1000 860 times 10minus4
858 times 10minus4
855 times 10minus4
824 times 10minus4
119901119901 rarr 119887119892 + 119883
500 740 times 10minus1
739 times 10minus1
721 times 10minus1
516 times 10minus1
600 483 times 10minus1
480 times 10minus1
481 times 10minus1
398 times 10minus1
700 322 times 10minus1
322 times 10minus1
320 times 10minus1
289 times 10minus1
800 224 times 10minus1
221 times 10minus1
221 times 10minus1
204 times 10minus1
900 15 times 10minus1
158 times 10minus1
158 times 10minus1
149 times 10minus1
1000 114 times 10minus1
114 times 10minus1
113 times 10minus1
110 times 10minus1
119901119901 rarr 119887119885 + 119883
500 689 times 10minus2
685 times 10minus2
645 times 10minus2
423 times 10minus2
600 452 times 10minus2
451 times 10minus2
434 times 10minus2
353 times 10minus2
700 312 times 10minus2
311 times 10minus2
305 times 10minus2
265 times 10minus2
800 219 times 10minus2
218 times 10minus2
215 times 10minus2
195 times 10minus2
900 156 times 10minus2
156 times 10minus2
155 times 10minus2
144 times 10minus2
1000 114 times 10minus2
113 times 10minus2
113 times 10minus2
107 times 10minus2
Table 13 The same as Table 11 but for parametrization PIII
SignalMass (GeV)
PIII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887120574 + 119883
500 131 times 10minus2
1314 times 10minus2
1275 times 10minus2
892 times 10minus2
600 859 times 10minus2
858 times 10minus2
844 times 10minus2
703 times 10minus2
700 582 times 10minus2
582 times 10minus2
577 times 10minus2
517 times 10minus2
800 407 times 10minus2
407 times 10minus2
406 times 10minus2
377 times 10minus2
900 292 times 10minus2
292 times 10minus2
291 times 10minus2
277 times 10minus2
1000 214 times 10minus2
213 times 10minus2
213 times 10minus2
206 times 10minus2
119901119901 rarr 119887119892 + 119883
500 1904 times 100
1896 times 100
1843 times 100
1286 times 100
600 1219 times 100
1213 times 100
1193 times 100
992 times 100
700 808 times 100
807 times 100
802 times 100
717 times 100
800 557 times 100
557 times 100
555 times 100
515 times 100
900 394 times 100
394 times 100
394 times 100
374 times 100
1000 285 times 100
285 times 100
285 times 100
274 times 100
119901119901 rarr 119887119885 + 119883
500 176 times 100
175 times 100
165 times 100
105 times 100
600 115 times 100
114 times 100
111 times 100
880 times 10minus1
700 783 times 10minus1
780 times 10minus1
760 times 10minus1
661 times 10minus1
800 547 times 10minus1
541 times 10minus1
531 times 10minus1
480 times 10minus1
900 392 times 10minus1
390 times 10minus1
382 times 10minus1
360 times 10minus1
1000 286 times 10minus1
282 times 10minus1
280 times 10minus1
262 times 10minus1
Advances in High Energy Physics 11
Table 14 The cross sections (in pb) for the backgrounds (119887(119887)119881 119888(119888)119881 and 119895119881 where119881 = photon jet and 119885 boson) with 119901119879cuts on the jets
and photon at the center of mass energy radic119904 = 13TeV
Background 119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887(119887)120574 + 119883 299 times 103
135 times 102
904 times 100
402 times 10minus1
119901119901 rarr 119888(119888)120574 + 119883 187 times 104
815 times 102
540 times 101
243 times 100
119901119901 rarr 119895120574 + 119883 543 times 104
327 times 103
338 times 102
285 times 101
119901119901 rarr 119887(119887)119895 + 119883 783 times 106
305 times 105
192 times 104
893 times 102
119901119901 rarr 119888(119888)119895 + 119883 122 times 107
455 times 105
289 times 104
135 times 103
119901119901 rarr 119895119895 + 119883 243 times 108
854 times 106
544 times 105
280 times 104
119901119901 rarr 119887(119887)119885 + 119883 502 times 102
135 times 102
225 times 101
156 times 100
119901119901 rarr 119888(119888)119885 + 119883 596 times 102
158 times 102
264 times 101
183 times 100
119901119901 rarr 119895119885 + 119883 800 times 103
208 times 103
408 times 102
412 times 101
500 600 700 800 900 1000
Mb998400 (GeV)
10minus1
100
101
102
103
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Figure 13 Integrated luminosity required to reach 3120590 significancefor the signal of 1198871015840 anomalous interactions for parametrization PI atthe LHC withradic119904 = 13TeV
500 600 700 800 900 1000
Mb998400 (GeV)
104
101
102
103
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Figure 14 The same as Figure 13 but for parametrization PII
500 600 700 800 900 100010minus1
100
101
102
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Mb998400 (GeV)
Figure 15 The same as Figure 13 but for parametrization PIII
parameters to include detector effects such as tracking tag-ging efficiencies and smearing effects After the simulationthe typical kinematical distributions are shown in Figures 17-18
In the analysis the signal (with 120581Λ = 03TeVminus1 and1198981198871015840 = 700GeV) and the corresponding background are
taken into account The invariant mass of the new heavyquark 1198871015840 can be reconstructed from a 119887jet and a neutral gaugeboson (where the 119885 boson can also be reconstructed fromits dilepton or hadronic decay) For the 119887120574 production werequire a large 119901120574
119879(gt100GeV) for photon and large 119901119895
119879
(gt100GeV) for jet and pseudorapidity |120578119895120574| (lt25) For the 119887120574signal channel the invariantmass distributions for signal andbackground events are shown in Figure 19The large 119901119895120574
119879and
the requirement of single 119887-tagging allow a better separationof the signal (for 119887120574 channel) from the background and thenwe find a precise limit for the anomalous coupling in thischannel For the 119887119892 and 119887119885 production we require two high119901119879jets (one 119887-jet) and a high 119901
119879jet in addition to the
reconstructed mass 119898rec119885 respectively The main character of
12 Advances in High Energy Physics
500 600 700 800 900 100001
02
03
04
05120581Λ
(TeV
minus1 )
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Mb998400 (GeV)
Figure 16The contour plot of anomalous coupling andmass of newheavy quark 1198871015840 for the dynamical parametrization explained in thetext with a significance of 3120590 atradic119904 = 13TeV and 119871 int = 100fb
minus1
50 100 150 200 250 300 350 400
Entr
ies
0
2000
4000
6000
8000
10000
PhotonJet 1
pT (GeV)
Figure 17 Transverse momentum distributions of leading jet andphoton (119887120574 production) for signal after detector simulation
the signal is the high 119901119895119879andor 119901120574
119879and single 119887-tagged jet
We calculate the signal and background events in the range|119898
rec1198871015840 (GeV) minus 700GeV| lt 50GeV and we find a similar
significance as shown in Figure 16
5 Conclusion
The new heavy quarks of up-type and down-type can be pro-duced with large numbers at the LHC if they have the anoma-lous couplings (via flavor changing neutral current) thatwell dominate over the charged current interactions The
Entr
ies
50 100 150 200 250 300 350 4000
2000
4000
6000
8000
10000
12000
PhotonJet 1
pT (GeV)
Figure 18 Transverse momentum distributions of leading jet andphoton (119895120574 production) for background at the given conditionsmentioned in the text
500 550 600 650 700 750 800 850 900 950 10000
500
1000
1500
2000
2500
3000
BackgroundSignal
Mrecb998400
(GeV)
Even
ts10
GeV
Figure 19The reconstructedmass distributions for background andsignal (119887120574) with119898
1198871015840 = 700GeV and 120581Λ = 03TeVminus1
single production of new heavy quarks can be achievedthrough the anomalous interactions at the LHC with radic119904 =13TeV The anomalous vertices could appear significantly atleading order processes due to the possibility of new heavyquarks From the results of signal significance calculationsfor 1199051015840 (1198871015840) anomalous productions the sensitivity to theanomalous couplings 120581119905
1015840
Λ (1205811198871015840
Λ) can be reached down to010 TeVminus1 (015 TeVminus1) in the lepton + 119887jet + jet +MET (119887jet +jet) channel at radic119904 = 13TeV assuming a dynamical para-metrization for the anomalous couplings and the mass of 750GeV for the new heavy quarks The observability limits onthe anomalous couplings obtained after the simulation arecomparable with the partonic level analysis in the photon and119885 boson associated channels whereas the productions 119905119892 and119887119892 are less comparable due to the fast simulation method In
Advances in High Energy Physics 13
any case the single 119887 tagging will play an important role inprobing new heavy quarks and reducing the background
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgment
This work was supported in part by Turkish Atomic EnergyAuthority (TAEA) under Project Grant no 2011TAEKCERN-A5H2P101-19
References
[1] H J He N Polonsky and S F Su ldquoExtra families Higgs spec-trum and oblique correctionsrdquo Physical Review D vol 64 no5 Article ID 053004 11 pages 2001
[2] B Holdom W S Hou T Hurth M L Mangano S Sultansoyand G Unel ldquoFour statements about the fourth generationrdquoPMC Physics A vol 3 article 4 2009
[3] A Atre M Carena T Han and J Santiago ldquoHeavy quarksabove the top at the Tevatronrdquo Physical ReviewD vol 79 ArticleID 054018 2009
[4] A Atre G Azuelos M Carena et al ldquoModel-independentsearches for new quarks at the LHCrdquo Journal of High EnergyPhysics vol 2011 no 8 article 080 2011
[5] N Chen and H J He ldquoLHC signatures of two-Higgs-doubletswith fourth familyrdquo Journal of High Energy Physics vol 2012article 062 2012
[6] M S Chanowitz ldquoElectroweak constraints on the fourth gener-ation at two loop orderrdquo Physical Review D vol 88 Article ID015012 2013
[7] S Chakdar K Ghosh S Nandi and S K Rai ldquoCollider signa-tures of mirror fermions in the framework of a left-right mirrormodelrdquo Physical Review D vol 88 Article ID 095005 2013
[8] X F Wang C Du and H J He ldquoLHC Higgs signatures fromtopflavor seesaw mechanismrdquo Physics Letters B vol 723 no 4-5 pp 314ndash323 2013
[9] S Bar-Shalom M Geller S Nandi and A Soni ldquoTwo higgsdoublets a 4th generation and a 125GeV higgs a reviewrdquoAdvances in High Energy Physics vol 2013 Article ID 67297228 pages 2013
[10] H Fritzsch and D Holtmannspotter ldquoThe production of singlet-quarks at LEP and HERArdquo Physics Letters B vol 457 no 1ndash3pp 186ndash192 1999
[11] G Aad B Abbott J Abdallah et al ldquoSearch for down-typefourth generation quarks with the ATLAS detector in eventswith one lepton and hadronically decaying119882 bosonsrdquo PhysicalReview Letters vol 109 Article ID 032001 2012
[12] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoSearchfor pair produced fourth-generation up-type quarks in ppcollisions atradic119904 = 7 TeV with a lepton in the final staterdquo PhysicsLetters B vol 718 pp 307ndash328 2012
[13] G Aad B Abbott J Abdallah et al ldquoSearch for pair and singleproduction of new heavy quarks that decay to a Z boson and athird-generation quark in pp collisions at radic119904 = 8TeV with theATLAS detectorrdquo Journal of High Energy Physics vol 2014 no11 article 104 2014
[14] G Aad T Abajyan B Abbott et al ldquoSearch for pair productionof heavy top-like quarks decaying to a high-pTW boson and ab quark in the lepton plus jets final state at radic119904 = 7TeV with theATLAS detectorrdquo Physics Letters B vol 718 no 4ndash5 pp 1284ndash1302 2013
[15] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoSearchfor heavy top-like quark pair production in the dilepton finalstate in pp collisions at radic119904 = 7TeVrdquo Physics Letters B vol 716no 1 pp 103ndash121 2012
[16] G Aad B Abbott J Abdallah et al ldquoSearch for heavy vector-like quarks coupling to light quarks in protonndashproton collisionsat radic119904 = 7 Tev with the ATLAS detectorrdquo Physics Letters B vol712 no 1-2 pp 22ndash39 2012
[17] G Aad T Abajyan B Abbott et al ldquoSearch for a heavy top-quark partner in final states with two leptons with the ATLASdetector at the LHCrdquo Journal of High Energy Physics vol 2012article 94 2012
[18] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoCom-bined search for the quarks of a sequential fourth generationrdquoPhysical Review D vol 86 no 11 Article ID 112003 20 pages2012
[19] R Ciftci ldquoAnomalous single production of the fourth gener-ation quarks at the CERN LHCrdquo Physical Review D vol 78Article ID 075018 2008
[20] I T Cakır H D Yıldız O Cakır and G Unel ldquoAnomalousresonant production of the fourth-family up-type quarks at theLHCrdquo Physical Review D vol 80 Article ID 095009 2009
[21] M Sahin S Sultansoy and S Turkoz ldquoSearching for the fourthfamily quarks through anomalous decaysrdquo Physical Review Dvol 82 no 5 Article ID 051503 2010
[22] M Bobrowski A Lenz J Riedl and J Rohrwild ldquoHow muchspace is left for a new family of fermionsrdquo Physical Review Dvol 79 no 11 Article ID 113006 15 pages 2009
[23] G Eilam B Melic and J Trampetic ldquo119862119875 violation and thefourth generationrdquo Physical Review D vol 80 no 11 Article ID116003 2009
[24] O Cobanoglu E Ozcan S Sultansoy and G Unel ldquoOPUCEMa library with error checkingmechanism for computing obliqueparametersrdquo Computer Physics Communications vol 182 no 8pp 1732ndash1743 2011
[25] T Han and J L Hewett ldquoTop-charm associated production inhigh energy 119890+119890minus collisionsrdquo Physical Review D vol 60 ArticleID 074015 1999
[26] A Belyaev N D Christensen and A Pukhov ldquoCalcHEP 34for collider physics within and beyond the standard modelrdquoComputer Physics Communications vol 184 no 7 pp 1729ndash1769 2013
[27] J Pumplin D Robert Stump J Huston H-L Lai P Nadolskyand W-K Tung ldquoNew generation of Parton distributions withuncertainties from global QCD analysisrdquo Journal of High EnergyPhysics vol 2002 article 012 2002
[28] G L Bayatian S Chatrchyan G Hmayakyan et al ldquoCMSphysics technical design report volume II physics perfor-mancerdquo Journal of Physics G Nuclear and Particle Physics vol34 no 6 p 995 2007
[29] T Sjostrand S Mrenna and P Skands ldquoPYTHIA 64 physicsand manualrdquo Journal of High Energy Physics vol 2006 no 5 p026 2006
[30] J Conway R Culbertson and R Demina Pretty Good Sim-ulation (PGS4) httpwwwphysicsucdavisedusimconwayresearchsoftwarepgspgs4-generalhtm
14 Advances in High Energy Physics
[31] EXROOTANALYSIS package for PGS4 data analysishttpmadgraphhepuiuceduDownloadsExRootAnalysis
[32] R Brun et al An object oriented data analysis framework(ROOT) httpsrootcernchdrupal
[33] F del Aguila and J A Aguilar-Saavedra ldquoMultilepton produc-tion via top flavour-changing neutral couplings at the CERNLHCrdquo Nuclear Physics B vol 576 pp 56ndash84 2000
[34] T Han M Hosch K Whisnant B-L Young and X ZhangldquoSingle top quark production via FCNC couplings at hadroncollidersrdquo Physical Review D vol 58 Article ID 073008 1998
[35] T Stelzer Z Sullivan and S Willenbrock ldquoSingle-top-quarkproduction at hadron collidersrdquoPhysical ReviewD vol 58 no 9Article ID 094021 11 pages 1998
Figure 1 Diagrams for the subprocess 119892119902 rarr 119881119876 with anomalous vertices 1198761015840119902119881 and 1198761015840119876119881 (where 1198761015840 can be the new heavy quark 1198871015840 or 1199051015840depending on the type of light (119902) or heavy (119876 equiv 119905 119887) quarks resp)
Table 3 Branching ratios () and decay width of the new heavyquark (1198871015840) with only anomalous interactions for PI parametrizationand 120581Λ = 01 TeVminus1
and PIII parametrization the branching ratios into 119887119881 (119881 =
119892 119885 120574) are larger than 119902119881 (119902 = 119889 119904) channels The 1199051015840 and1198871015840 decay widths are about the same values for PII and PIIIparametrization
4 The Cross Sections
In order to study the new heavy quark productions at theLHC we have used effective anomalous interaction verticesand implemented these vertices into the CalcHEP package[26] In all of the numerical calculations the parton dis-tribution functions are set to the CTEQ6L parametrization[27] The new heavy quarks can be produced through theiranomalous couplings to the ordinary quarks and neutralvector bosons as shown in Figure 1
Total cross sections for the productions of new heavyquarks 1199051015840 and 119887
1015840 are given in Tables 5 and 6 for theparametrizations PI PII and PIII at the center of massenergy of 8 TeV and 13 TeV For an illustration taking themass of new heavy quarks as 700GeV the cross section of1199051015840(1198871015840) production is calculated as 850 pb (1003 pb) for the
parametrization PIII at radic119904 = 13TeV It can be seen fromTables 5 and 6 that the cross section decreases while the
PIIIPIPII
10minus1
100
101
102
500 600 700 800 900 1000
120590(p
b)
Mt998400 (GeV)
Figure 2The cross section for the process 119901119901 rarr 119905119881+119883 dependingon the mass for parameter sets PI PII and PIII at the center of massenergyradic119904 = 13TeV
mass of the new heavy quark increases The cross section for1199051015840 production is larger than the 1198871015840 production with a factor of12ndash18 (07ndash10) for PI (PII and PIII) parametrization depend-ing on the consideredmass range atradic119904 = 13TeVThe generalbehaviour of the production cross sections depending on themass of new heavy quarks is presented in Figures 2 and 3 fordifferent parametrizations
41 Analysis of the Process 119901119901 rarr 119882+119887119881+119883 (119881 = 119892 119885 120574) for
1199051015840 Signal The signal process 119901119901 rarr 119882
includes the 1199051015840 exchange in both the 119904-channel and 119905-channelThe 119904-channel contribution to the signal process wouldappear itself as resonance around the 1199051015840 mass value in the119882119887119881 invariant mass The 119905-channel gives the nonresonant
4 Advances in High Energy Physics
Table 4 The same as Table 3 but for PII (PIII) parametrization
Table 5The cross sections (in pb) of new heavy quark 1199051015840 production without cuts for PI PII and PIII parametrizations at the center of massenergy 13TeV (8TeV) respectively
Mass (GeV) PI PII PIIIradic119904 = 13 TeV (8 TeV) radic119904 = 13 TeV (8 TeV) radic119904 = 13 TeV (8 TeV)
Figure 3The cross section for the process119901119901 rarr 119887119881+119883 dependingon the new heavy quark mass for parameter sets PI PII and PII atthe center of mass energyradic119904 = 13TeV
contribution We consider that the 119882 boson decays intolepton + missing transverse momentum with the branchingratio of 21 and 119885 boson decays into dilepton with thebranching ratio of 67 In our analyses we consider the 1199051015840signal in the 119897 + 119887jet + 120574 + MET 119897 + 119887jet + 119895 + MET and3119897 + 119887jet +MET channels where 119897 = 119890 120583 However if one takesthe hadronic119882 decay the signal will be enhanced by a factorof BR(119882 rarr hadrons)BR(119882 rarr 119897])
We have obtained the cross sections by using the cutspseudorapidity |120578
119895120574| lt 25 and transverse momentum 119901
119895120574
119879gt
20ndash200GeV for jets and photon in Table 7 (Tables 8 and 9)
500 600 700 800 900 100010minus6
10minus5
10minus4
10minus3
10minus2
10minus1
100
d120590d
mtV
(pb
GeV
)
MtV (GeV)
pp rarr tg + X
pp rarr tZ + X
pp rarr t120574 + X
Figure 4 Invariant mass distributions 119898119905119881
(where 119881 = 120574 119892 and119885) for PI parametrization of the signal with 120581Λ = 02TeVminus1 and1198981199051015840 = 700GeV at the center of mass energy radic119904 = 13TeV
for PI (PII PIII) parametrization respectively Invariantmassdistribution of the 119905119881 (where 119881 = 120574 119892 and 119885) system isshown in Figure 4 for PI parametrization of the signal with120581Λ = 02TeVminus1 and 119898
1199051015840 = 700GeV at the center of mass
energy radic119904 = 13TeV It appears from signal significance cal-culations that the optimized transverse momentum cut is119901119895120574
119879gt 100GeV for 1199051015840 analysesThe backgrounds for the final state119882+119887(119887)119881 (where 119881 equiv
photon jet and 119885 boson) are given in Table 10 We apply thefollowing cuts to the final state photon and jets as |120578
119895120574| lt 25
and 119901119895120574119879
gt 20ndash200GeV For the background cross section
Advances in High Energy Physics 5
Table 6The cross sections (in pb) of new heavy quark 1198871015840 production without cuts for PI PII and PIII parametrizations at the center of massenergy of 13TeV (8TeV) respectively
Mass (GeV) PI PII PIIIradic119904 = 13 TeV (8 TeV) radic119904 = 13 TeV (8 TeV) radic119904 = 13 TeV (8 TeV)
Table 7 The cross sections (in pb) for 1199051015840 signal in different decay channels for PI parametrization with 119901119879cuts on the jets and photon and
|120578119895120574| lt 25 at the center of mass energyradic119904 = 13TeV
SignalMass (GeV)
PI119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119882+119887120574 + 119883
500 289 times 10minus1
210 times 10minus1
124 times 10minus1
102 times 10minus4
600 243 times 10minus1
164 times 10minus1
119 times 10minus1
123 times 10minus2
700 168 times 10minus1
12 times 10minus1
112 times 10minus1
225 times 10minus2
800 130 times 10minus1
103 times 10minus1
753 times 10minus2
325 times 10minus2
900 102 times 10minus1
808 times 10minus2
696 times 10minus2
302 times 10minus2
1000 761 times 10minus2
635 times 10minus2
507 times 10minus2
294 times 10minus2
119901119901 rarr 119882+119887119892 + 119883
500 778 times 100
602 times 100
363 times 100
474 times 10minus3
600 630 times 100
518 times 100
313 times 100
258 times 10minus1
700 499 times 100
363 times 100
304 times 100
932 times 10minus1
800 401 times 100
345 times 100
276 times 100
991 times 10minus1
900 332 times 100
277 times 100
213 times 100
108 times 100
1000 258 times 100
227 times 100
188 times 100
101 times 100
119901119901 rarr 119882+119887119885+119883
500 796 times 10minus1
601 times 10minus1
301 times 10minus1
101 times 10minus4
600 479 times 10minus1
386 times 10minus1
245 times 10minus1
271 times 10minus3
700 399 times 10minus1
312 times 10minus1
239 times 10minus1
696 times 10minus2
800 331 times 10minus1
289 times 10minus1
209 times 10minus1
805 times 10minus2
900 273 times 10minus1
273 times 10minus1
191 times 10minus1
954 times 10minus2
1000 223 times 10minus1
202 times 10minus1
161 times 10minus1
910 times 10minus2
estimates we assume the efficiency for 119887-tagging to be 120576119887=
50 and the rejection ratios to be 10 for 119888 (119888) quark jets and1 for light quark jets since they are assumed to bemistaggedas 119887-jets
In order to find the discovery limits we use the statisticalsignificance [28] defined as
where 119878 and 119861 are the numbers of the signal and backgroundevents respectively In Figures 5ndash7 the integrated luminosityrequired to reach 3120590 significance for the signal of 1199051015840 anoma-lous interactions is shown for parametrizations PI PII andPIII at the LHC with radic119904 = 13 TeV It is seen from these
figures that the channel 1199051015840 rarr 119905119885 requires more integratedluminosity than the other channels By requiring the signalsignificance 119878119878 = 3 the contour plots of 120581Λ and mass of1199051015840 quark are presented in Figure 8 The results show that onecan discover the 1199051015840 quark anomalous couplings 120581Λ down to01 TeVminus1 in the 119905119892 channel for119898
1199051015840 = 750GeV
411 Simulation for 1199051015840 Signal In order to include detectoreffects in the simulation we have generated 119905119881 (where 119881 =
120574 119892 and 119885) signal events for each subprocess and they aremixed using the ldquoevent mixerrdquo script which can be foundwithin the CALCHEP package [26] For further decay andhadronization these events are passed to PYTHIA [29] andsimulated with the PGS4 program [30] using generic LHC
6 Advances in High Energy Physics
Table 8 The same as Table 7 but for parametrization PII
SignalMass (GeV)
PII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119882+119887120574 + 119883
500 678 times 10minus3
507 times 10minus3
345 times 10minus3
264 times 10minus7
600 657 times 10minus3
542 times 10minus3
347 times 10minus3
534 times 10minus4
700 502 times 10minus3
431 times 10minus3
304 times 10minus3
873 times 10minus4
800 391 times 10minus3
376 times 10minus3
256 times 10minus3
103 times 10minus3
900 303 times 10minus3
268 times 10minus3
211 times 10minus3
101 times 10minus3
1000 240 times 10minus3
243 times 10minus3
177 times 10minus3
998 times 10minus4
119901119901 rarr 119882+119887119892 + 119883
500 347 times 10minus1
268 times 10minus1
152 times 10minus1
530 times 10minus6
600 251 times 10minus1
212 times 10minus1
135 times 10minus1
201 times 10minus2
700 187 times 10minus1
16 times 10minus1
116 times 10minus1
342 times 10minus2
800 146 times 10minus1
125 times 10minus1
939 times 10minus2
403 times 10minus2
900 112 times 10minus1
108 times 10minus1
780 times 10minus2
386 times 10minus2
1000 935 times 10minus2
837 times 10minus2
662 times 10minus2
368 times 10minus2
119901119901 rarr 119882+119887119885+119883
500 210 times 10minus2
177 times 10minus2
116 times 10minus2
264 times 10minus7
600 195 times 10minus2
175 times 10minus2
114 times 10minus2
134 times 10minus3
700 173 times 10minus2
143 times 10minus2
100 times 10minus2
29 times 10minus3
800 134 times 10minus2
119 times 10minus2
889 times 10minus3
342 times 10minus3
900 106 times 10minus2
955 times 10minus3
763 times 10minus3
337 times 10minus3
1000 809 times 10minus3
758 times 10minus3
631 times 10minus3
323 times 10minus3
Table 9 The same as Table 7 but for parametrization PIII
SignalMass (GeV)
PIII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119882+119887120574 + 119883
500 260 times 10minus1
278 times 10minus1
108 times 10minus1
159 times 10minus4
600 178 times 10minus1
161 times 10minus1
101 times 10minus1
142 times 10minus2
700 156 times 10minus1
135 times 10minus1
933 times 10minus2
272 times 10minus2
800 117 times 10minus1
106 times 10minus1
784 times 10minus2
332 times 10minus2
900 904 times 10minus2
842 times 10minus2
668 times 10minus2
325 times 10minus2
1000 760 times 10minus2
676 times 10minus2
516 times 10minus2
317 times 10minus2
119901119901 rarr 119882+119887119892 + 119883
500 839 times 100
649 times 100
386 times 100
465 times 10minus3
600 610 times 100
578 times 100
381 times 100
556 times 10minus1
700 539 times 100
464 times 100
341 times 100
970 times 10minus1
800 394 times 100
354 times 100
273 times 100
105 times 100
900 324 times 100
276 times 100
227 times 100
107 times 100
1000 233 times 100
229 times 100
184 times 100
998 times 10minus1
119901119901 rarr 119882+119887119885+119883
500 772 times 10minus1
101 times 100
217 times 10minus1
627 times 10minus4
600 624 times 10minus1
385 times 10minus1
292 times 10minus1
320 times 10minus2
700 500 times 10minus1
305 times 10minus1
286 times 10minus1
580 times 10minus2
800 378 times 10minus1
250 times 10minus1
242 times 10minus1
964 times 10minus2
900 304 times 10minus1
167 times 10minus1
206 times 10minus1
962 times 10minus2
1000 251 times 10minus1
129 times 10minus1
148 times 10minus1
961 times 10minus2
Advances in High Energy Physics 7
Table 10The cross sections (in pb) for the relevant backgrounds (119882+119887(119887)119881119882+119888(119888)119881 and119882+119895119881 where119881 = photon jet and119885 boson) with119901119879cuts on the jets at the center of mass energyradic119904 = 13TeV
Background 119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119882+119887120574 + 119883 237 times 10
minus3362 times 10
minus4617 times 10
minus5699 times 10
minus6
119901119901 rarr 119882+119888120574 + 119883 415 times 10
0459 times 10
minus1625 times 10
minus2621 times 10
minus3
119901119901 rarr 119882+119895120574 + 119883 263 times 10
1430 times 10
0733 times 10
minus1127 times 10
minus1
119901119901 rarr 119882+119887(119887)119895 + 119883 726 times 10
1302 times 10
1611 times 10
0974 times 10
minus1
119901119901 rarr 119882+119888(119888)119895 + 119883 598 times 10
2965 times 10
1179 times 10
1242 times 10
0
119901119901 rarr 119882+119895119895 + 119883 731 times 10
3778 times 10
2161 times 10
2258 times 10
1
119901119901 rarr 119882+119887119885 + 119883 626 times 10
minus4399 times 10
minus4193 times 10
minus4471 times 10
minus5
119901119901 rarr 119882+119888119885 + 119883 529 times 10
minus1340 times 10
minus1166 times 10
minus1415 times 10
minus2
119901119901 rarr 119882+119895119885 + 119883 859 times 10
0483 times 10
0249 times 10
0791 times 10
minus1
500 600 700 800 900 100010minus2
10minus1
100
101
102
103
t998400 rarr tZ
t998400 rarr t120574
t998400 rarr tg
Mt998400 (GeV)
Lin
t(fb
minus1)
Figure 5 Integrated luminosity required to reach 3120590 significancefor the signal of 1199051015840 anomalous interactions for parametrization PI atthe LHC withradic119904 = 13TeV
102
103
104
500 600 700 800 900 1000
t998400 rarr tZ
t998400 rarr t120574
t998400 rarr tg
Mt998400 (GeV)
Lin
t(fb
minus1)
Figure 6 The same as Figure 5 but for parametrization PII
500 600 700 800 900 100010minus2
10minus1
100
101
102
103
t998400 rarr tZ
t998400 rarr t120574
t998400 rarr tg
Mt998400 (GeV)
Lin
t(fb
minus1)
Figure 7 The same as Figure 5 but for parametrization PIII
detector parametersThis fast simulation includes the impor-tant detector effects such as tracking smearing effects of thecalorimeters resolution and tag efficiencies The EXROOT-ANALYSIS package [31] is used for the simulated events andthe output is analyzed and histogrammed with the ROOT[32] macros We consider jets (up to five) leptons (electronsor muons) photons and missing transverse momentumwithin the simulated events for the 119905120574 119905119895 and 119905119885 eventsgeneration The typical kinematical distributions are shownin Figures 9-10
In the analysis the signal (with 120581Λ = 02TeVminus1 and1198981199051015840 = 700GeV) and the corresponding background (119882119895119881)
are taken into accountThe 119904-channel contribution to the sig-nal process appears as a resonance around the 1199051015840mass value inthe reconstructed invariant mass 119898rec
1199051015840 The reconstructed
mass distribution for the 1199051015840 signal (reconstructed from a topquark and a vector boson) is shown in Figure 11
Similar to the single top processes the top quark in thefinal state is reconstructed from a leading jet (commonly 119887jet)and a119882 boson (which can be reconstructed from its leptonicor hadronic decay) For the 119905120574 production we require
8 Advances in High Energy Physics
500 600 700 800 900 1000
Mt998400 (GeV)
01
02
03
04
05120581Λ
(TeV
minus1 )
t998400 rarr WbZ
t998400 rarr Wb120574
t998400 rarr Wbg
Figure 8The contour plot of anomalous coupling and mass of newheavy quark 1199051015840 for the dynamical parametrization explained in thetext with a significance of 3120590 atradic119904 = 13TeV and 119871 int = 100fb
minus1
50 100 150 200 250 300 350 400
Entr
ies
0
2000
4000
6000
8000
10000
12000
14000
16000
PhotonJet 1
Jet 2Jet 3
pT (GeV)
Figure 9 Transverse momentum distributions of leading jet (Jet 1)and other jets (Jet 2 and Jet 3) and photon for signal (119905120574 production)after detector simulation
systematically the large transverse momentum of photon(119901120574119879gt 100GeV) minimum jet transverse momentum (119901119895
119879gt
20GeV) and the pseudorapidity range (|120578119895120574| lt 25) inaddition to the requirements on mass reconstruction of119882-boson and top quark The large 119901120574
119879and the requirement of
single 119887-tagging allow a better separation of the signal (for 119905120574channel) from the background Other channels for 119905119892 and 119905119885productions are more challenging due to a large number ofjets which require additional discriminators such as angularandor total transverse energy variables However in orderto get rid of the backgrounds from 119882119905 and 119905119905 production
Entr
ies
50 100 150 200 250 300 350 4000
5000
10000
15000
20000
25000
PhotonJet 1
Jet 2Jet 3
pT (GeV)
Figure 10 Transverse momentum distributions of leading jet (Jet1) and other jets (Jet 2 and Jet 3) and photon for background (119882119895120574production)
500 600 700 800 900 1000
40
60
80
100
120
BackgroundSignal
Mrect998400
(GeV)
Even
ts10
GeV
Figure 11The reconstructedmass distributions for background andsignal (119905120574) with119898
1199051015840 = 700GeV and 120581Λ = 015TeVminus1
(for a similar framework the production cross sections areabout 25 pb and 340 pb resp) one can consider the channel3119897 + 119887jet + MET for a distinctive signal from the 1199051015840 rarr 119905119885An analysis of the investigation of single top production withsimilar backgrounds at the LHC can be found in [33ndash35]
42 Analysis of the Process 119901119901 rarr 119887119881 + 119883 (119881 = 119892 119885 120574) for1198871015840 Signal The signal process 119901119901 rarr 119887119881 + 119883 (119881 = 119892 119885 120574)includes the new heavy quark 1198871015840 exchange in both the 119904-channel and the 119905-channel The 119904-channel contributes to thesignal process as resonance around the 1198871015840mass value in the 119887119881invariantmass while the 119905-channel contributes to the nonres-onant behaviour For this process we consider the leptonicdecay of 119885 boson In the analyses we consider the 1198871015840 signalto be 119887jet + 120574 119887jet + 119895 and 119887jet + dilepton
Advances in High Energy Physics 9
Table 11 The cross sections (in pb) for 1198871015840 signal in different decay channel for parametrization PI with 119901119879cuts on the jets and photon and
|120578119895120574| lt 25 at the center of mass energyradic119904 = 13TeV
SignalMass (GeV)
PI119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887120574 + 119883
500 564 times 10minus2
562 times 10minus2
549 times 10minus2
395 times 10minus2
600 396 times 10minus2
396 times 10minus2
390 times 10minus2
333 times 10minus2
700 287 times 10minus2
287 times 10minus2
286 times 10minus2
259 times 10minus2
800 212 times 10minus2
213 times 10minus2
212 times 10minus2
199 times 10minus2
900 160 times 10minus2
160 times 10minus2
160 times 10minus2
153 times 10minus2
1000 122 times 10minus2
122 times 10minus2
122 times 10minus2
119 times 10minus2
119901119901 rarr 119887119892 + 119883
500 813 times 100
813 times 100
793 times 100
596 times 100
600 559 times 100
559 times 100
553 times 100
488 times 100
700 398 times 100
398 times 100
396 times 100
373 times 100
800 291 times 100
291 times 100
290 times 100
281 times 100
900 216 times 100
216 times 100
216 times 100
214 times 100
1000 164 times 100
163 times 100
163 times 100
162 times 100
119901119901 rarr 119887119885 + 119883
500 787 times 10minus1
781 times 10minus1
750 times 10minus1
479 times 10minus1
600 548 times 10minus1
548 times 10minus1
531 times 10minus1
427 times 10minus1
700 395 times 10minus1
394 times 10minus1
386 times 10minus1
339 times 10minus1
800 292 times 10minus1
291 times 10minus1
286 times 10minus1
261 times 10minus1
900 218 times 10minus1
218 times 10minus1
215 times 10minus1
202 times 10minus1
1000 166 times 10minus1
166 times 10minus1
164 times 10minus1
156 times 10minus1
We have obtained the cross sections by using the pseu-dorapidity cuts |120578
119895120574| lt 25 and transverse momentum cuts
119901119895120574
119879gt 20ndash200GeV for jets and photon in Table 11 (Tables
12 and 13) for PI (PII PIII) parametrizations respectivelyInvariantmass distribution of the 119887119881 (where119881 = 120574 119892 and119885)system is shown in Figure 12 for PI parametrization of thesignal with 120581Λ = 02TeVminus1 and 119898
1198871015840 = 700GeV at the
center of mass energy radic119904 = 13TeV It appears from sig-nal significance calculation that the optimized transversemomentum cut is 119901
119879gt 200GeV for 1198871015840 analyses
The backgrounds for the final state 119887(119887)119881 (where 119881 equiv
photon jet and 119885 boson) are given in Table 14 We apply thefollowing cuts to the final state photon and jets as |120578
119895120574| lt 25
and 119901119895120574119879gt 20ndash200GeV It can be noted that the background
cross section decreases as the119901119879cuts increaseWe assume the
efficiency for 119887-tagging to be 120576119887= 50and the rejection ratios
to be 10 for 119888 (119888) quark jets and 1 for light quark jetsIn order to reach 3120590 significance for the signal of 1198871015840
anomalous interactions the required integrated luminosityis shown in Figures 13ndash15 for parametrizations PI PII andPIII at the LHC with radic119904 = 13TeV The channel 1198871015840 rarr 119887120574
requires more integrated luminosity than the other channelsBy requiring the signal significance 119878119878 = 3 the contour plotsof 120581Λ and mass of 1198871015840 quark are presented in Figure 16 Theresults show that one can discover the 1198871015840 quark anomalouscouplings down to 01 in the 119887119892 channel for119898
1198871015840 = 500GeV
500 600 700 800 900 100010minus6
10minus5
10minus4
10minus3
10minus2
10minus1
100
d120590d
mbV
(pb
GeV
)
MbV (GeV)
pp rarr bg + X
pprarr bZ + X
pprarr b120574 + X
Figure 12 Invariant mass distribution of the 119887119881 (where 119881 = 120574 119892and 119885) system is shown in Figure 5 for PI parametrization of thesignal with 120581Λ = 02TeVminus1 and 119898
1198871015840 = 700GeV at the center of
mass energyradic119904 = 13TeV
421 Simulation for 1198871015840 Signal In the simulation we havegenerated 119887119881 (where 119881 = 120574 119892 and 119885) events for each sub-process and these events are simulated using generic detector
10 Advances in High Energy Physics
Table 12 The same as Table 11 but for parametrization PII
SignalMass (GeV)
PII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887120574 + 119883
500 518 times 10minus3
526 times 10minus3
504 times 10minus3
354 times 10minus3
600 338 times 10minus3
337 times 10minus3
336 times 10minus3
277 times 10minus3
700 232 times 10minus3
231 times 10minus3
230 times 10minus3
205 times 10minus3
800 171 times 10minus3
163 times 10minus3
164 times 10minus3
150 times 10minus3
900 117 times 10minus3
116 times 10minus3
117 times 10minus3
111 times 10minus3
1000 860 times 10minus4
858 times 10minus4
855 times 10minus4
824 times 10minus4
119901119901 rarr 119887119892 + 119883
500 740 times 10minus1
739 times 10minus1
721 times 10minus1
516 times 10minus1
600 483 times 10minus1
480 times 10minus1
481 times 10minus1
398 times 10minus1
700 322 times 10minus1
322 times 10minus1
320 times 10minus1
289 times 10minus1
800 224 times 10minus1
221 times 10minus1
221 times 10minus1
204 times 10minus1
900 15 times 10minus1
158 times 10minus1
158 times 10minus1
149 times 10minus1
1000 114 times 10minus1
114 times 10minus1
113 times 10minus1
110 times 10minus1
119901119901 rarr 119887119885 + 119883
500 689 times 10minus2
685 times 10minus2
645 times 10minus2
423 times 10minus2
600 452 times 10minus2
451 times 10minus2
434 times 10minus2
353 times 10minus2
700 312 times 10minus2
311 times 10minus2
305 times 10minus2
265 times 10minus2
800 219 times 10minus2
218 times 10minus2
215 times 10minus2
195 times 10minus2
900 156 times 10minus2
156 times 10minus2
155 times 10minus2
144 times 10minus2
1000 114 times 10minus2
113 times 10minus2
113 times 10minus2
107 times 10minus2
Table 13 The same as Table 11 but for parametrization PIII
SignalMass (GeV)
PIII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887120574 + 119883
500 131 times 10minus2
1314 times 10minus2
1275 times 10minus2
892 times 10minus2
600 859 times 10minus2
858 times 10minus2
844 times 10minus2
703 times 10minus2
700 582 times 10minus2
582 times 10minus2
577 times 10minus2
517 times 10minus2
800 407 times 10minus2
407 times 10minus2
406 times 10minus2
377 times 10minus2
900 292 times 10minus2
292 times 10minus2
291 times 10minus2
277 times 10minus2
1000 214 times 10minus2
213 times 10minus2
213 times 10minus2
206 times 10minus2
119901119901 rarr 119887119892 + 119883
500 1904 times 100
1896 times 100
1843 times 100
1286 times 100
600 1219 times 100
1213 times 100
1193 times 100
992 times 100
700 808 times 100
807 times 100
802 times 100
717 times 100
800 557 times 100
557 times 100
555 times 100
515 times 100
900 394 times 100
394 times 100
394 times 100
374 times 100
1000 285 times 100
285 times 100
285 times 100
274 times 100
119901119901 rarr 119887119885 + 119883
500 176 times 100
175 times 100
165 times 100
105 times 100
600 115 times 100
114 times 100
111 times 100
880 times 10minus1
700 783 times 10minus1
780 times 10minus1
760 times 10minus1
661 times 10minus1
800 547 times 10minus1
541 times 10minus1
531 times 10minus1
480 times 10minus1
900 392 times 10minus1
390 times 10minus1
382 times 10minus1
360 times 10minus1
1000 286 times 10minus1
282 times 10minus1
280 times 10minus1
262 times 10minus1
Advances in High Energy Physics 11
Table 14 The cross sections (in pb) for the backgrounds (119887(119887)119881 119888(119888)119881 and 119895119881 where119881 = photon jet and 119885 boson) with 119901119879cuts on the jets
and photon at the center of mass energy radic119904 = 13TeV
Background 119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887(119887)120574 + 119883 299 times 103
135 times 102
904 times 100
402 times 10minus1
119901119901 rarr 119888(119888)120574 + 119883 187 times 104
815 times 102
540 times 101
243 times 100
119901119901 rarr 119895120574 + 119883 543 times 104
327 times 103
338 times 102
285 times 101
119901119901 rarr 119887(119887)119895 + 119883 783 times 106
305 times 105
192 times 104
893 times 102
119901119901 rarr 119888(119888)119895 + 119883 122 times 107
455 times 105
289 times 104
135 times 103
119901119901 rarr 119895119895 + 119883 243 times 108
854 times 106
544 times 105
280 times 104
119901119901 rarr 119887(119887)119885 + 119883 502 times 102
135 times 102
225 times 101
156 times 100
119901119901 rarr 119888(119888)119885 + 119883 596 times 102
158 times 102
264 times 101
183 times 100
119901119901 rarr 119895119885 + 119883 800 times 103
208 times 103
408 times 102
412 times 101
500 600 700 800 900 1000
Mb998400 (GeV)
10minus1
100
101
102
103
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Figure 13 Integrated luminosity required to reach 3120590 significancefor the signal of 1198871015840 anomalous interactions for parametrization PI atthe LHC withradic119904 = 13TeV
500 600 700 800 900 1000
Mb998400 (GeV)
104
101
102
103
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Figure 14 The same as Figure 13 but for parametrization PII
500 600 700 800 900 100010minus1
100
101
102
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Mb998400 (GeV)
Figure 15 The same as Figure 13 but for parametrization PIII
parameters to include detector effects such as tracking tag-ging efficiencies and smearing effects After the simulationthe typical kinematical distributions are shown in Figures 17-18
In the analysis the signal (with 120581Λ = 03TeVminus1 and1198981198871015840 = 700GeV) and the corresponding background are
taken into account The invariant mass of the new heavyquark 1198871015840 can be reconstructed from a 119887jet and a neutral gaugeboson (where the 119885 boson can also be reconstructed fromits dilepton or hadronic decay) For the 119887120574 production werequire a large 119901120574
119879(gt100GeV) for photon and large 119901119895
119879
(gt100GeV) for jet and pseudorapidity |120578119895120574| (lt25) For the 119887120574signal channel the invariantmass distributions for signal andbackground events are shown in Figure 19The large 119901119895120574
119879and
the requirement of single 119887-tagging allow a better separationof the signal (for 119887120574 channel) from the background and thenwe find a precise limit for the anomalous coupling in thischannel For the 119887119892 and 119887119885 production we require two high119901119879jets (one 119887-jet) and a high 119901
119879jet in addition to the
reconstructed mass 119898rec119885 respectively The main character of
12 Advances in High Energy Physics
500 600 700 800 900 100001
02
03
04
05120581Λ
(TeV
minus1 )
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Mb998400 (GeV)
Figure 16The contour plot of anomalous coupling andmass of newheavy quark 1198871015840 for the dynamical parametrization explained in thetext with a significance of 3120590 atradic119904 = 13TeV and 119871 int = 100fb
minus1
50 100 150 200 250 300 350 400
Entr
ies
0
2000
4000
6000
8000
10000
PhotonJet 1
pT (GeV)
Figure 17 Transverse momentum distributions of leading jet andphoton (119887120574 production) for signal after detector simulation
the signal is the high 119901119895119879andor 119901120574
119879and single 119887-tagged jet
We calculate the signal and background events in the range|119898
rec1198871015840 (GeV) minus 700GeV| lt 50GeV and we find a similar
significance as shown in Figure 16
5 Conclusion
The new heavy quarks of up-type and down-type can be pro-duced with large numbers at the LHC if they have the anoma-lous couplings (via flavor changing neutral current) thatwell dominate over the charged current interactions The
Entr
ies
50 100 150 200 250 300 350 4000
2000
4000
6000
8000
10000
12000
PhotonJet 1
pT (GeV)
Figure 18 Transverse momentum distributions of leading jet andphoton (119895120574 production) for background at the given conditionsmentioned in the text
500 550 600 650 700 750 800 850 900 950 10000
500
1000
1500
2000
2500
3000
BackgroundSignal
Mrecb998400
(GeV)
Even
ts10
GeV
Figure 19The reconstructedmass distributions for background andsignal (119887120574) with119898
1198871015840 = 700GeV and 120581Λ = 03TeVminus1
single production of new heavy quarks can be achievedthrough the anomalous interactions at the LHC with radic119904 =13TeV The anomalous vertices could appear significantly atleading order processes due to the possibility of new heavyquarks From the results of signal significance calculationsfor 1199051015840 (1198871015840) anomalous productions the sensitivity to theanomalous couplings 120581119905
1015840
Λ (1205811198871015840
Λ) can be reached down to010 TeVminus1 (015 TeVminus1) in the lepton + 119887jet + jet +MET (119887jet +jet) channel at radic119904 = 13TeV assuming a dynamical para-metrization for the anomalous couplings and the mass of 750GeV for the new heavy quarks The observability limits onthe anomalous couplings obtained after the simulation arecomparable with the partonic level analysis in the photon and119885 boson associated channels whereas the productions 119905119892 and119887119892 are less comparable due to the fast simulation method In
Advances in High Energy Physics 13
any case the single 119887 tagging will play an important role inprobing new heavy quarks and reducing the background
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgment
This work was supported in part by Turkish Atomic EnergyAuthority (TAEA) under Project Grant no 2011TAEKCERN-A5H2P101-19
References
[1] H J He N Polonsky and S F Su ldquoExtra families Higgs spec-trum and oblique correctionsrdquo Physical Review D vol 64 no5 Article ID 053004 11 pages 2001
[2] B Holdom W S Hou T Hurth M L Mangano S Sultansoyand G Unel ldquoFour statements about the fourth generationrdquoPMC Physics A vol 3 article 4 2009
[3] A Atre M Carena T Han and J Santiago ldquoHeavy quarksabove the top at the Tevatronrdquo Physical ReviewD vol 79 ArticleID 054018 2009
[4] A Atre G Azuelos M Carena et al ldquoModel-independentsearches for new quarks at the LHCrdquo Journal of High EnergyPhysics vol 2011 no 8 article 080 2011
[5] N Chen and H J He ldquoLHC signatures of two-Higgs-doubletswith fourth familyrdquo Journal of High Energy Physics vol 2012article 062 2012
[6] M S Chanowitz ldquoElectroweak constraints on the fourth gener-ation at two loop orderrdquo Physical Review D vol 88 Article ID015012 2013
[7] S Chakdar K Ghosh S Nandi and S K Rai ldquoCollider signa-tures of mirror fermions in the framework of a left-right mirrormodelrdquo Physical Review D vol 88 Article ID 095005 2013
[8] X F Wang C Du and H J He ldquoLHC Higgs signatures fromtopflavor seesaw mechanismrdquo Physics Letters B vol 723 no 4-5 pp 314ndash323 2013
[9] S Bar-Shalom M Geller S Nandi and A Soni ldquoTwo higgsdoublets a 4th generation and a 125GeV higgs a reviewrdquoAdvances in High Energy Physics vol 2013 Article ID 67297228 pages 2013
[10] H Fritzsch and D Holtmannspotter ldquoThe production of singlet-quarks at LEP and HERArdquo Physics Letters B vol 457 no 1ndash3pp 186ndash192 1999
[11] G Aad B Abbott J Abdallah et al ldquoSearch for down-typefourth generation quarks with the ATLAS detector in eventswith one lepton and hadronically decaying119882 bosonsrdquo PhysicalReview Letters vol 109 Article ID 032001 2012
[12] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoSearchfor pair produced fourth-generation up-type quarks in ppcollisions atradic119904 = 7 TeV with a lepton in the final staterdquo PhysicsLetters B vol 718 pp 307ndash328 2012
[13] G Aad B Abbott J Abdallah et al ldquoSearch for pair and singleproduction of new heavy quarks that decay to a Z boson and athird-generation quark in pp collisions at radic119904 = 8TeV with theATLAS detectorrdquo Journal of High Energy Physics vol 2014 no11 article 104 2014
[14] G Aad T Abajyan B Abbott et al ldquoSearch for pair productionof heavy top-like quarks decaying to a high-pTW boson and ab quark in the lepton plus jets final state at radic119904 = 7TeV with theATLAS detectorrdquo Physics Letters B vol 718 no 4ndash5 pp 1284ndash1302 2013
[15] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoSearchfor heavy top-like quark pair production in the dilepton finalstate in pp collisions at radic119904 = 7TeVrdquo Physics Letters B vol 716no 1 pp 103ndash121 2012
[16] G Aad B Abbott J Abdallah et al ldquoSearch for heavy vector-like quarks coupling to light quarks in protonndashproton collisionsat radic119904 = 7 Tev with the ATLAS detectorrdquo Physics Letters B vol712 no 1-2 pp 22ndash39 2012
[17] G Aad T Abajyan B Abbott et al ldquoSearch for a heavy top-quark partner in final states with two leptons with the ATLASdetector at the LHCrdquo Journal of High Energy Physics vol 2012article 94 2012
[18] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoCom-bined search for the quarks of a sequential fourth generationrdquoPhysical Review D vol 86 no 11 Article ID 112003 20 pages2012
[19] R Ciftci ldquoAnomalous single production of the fourth gener-ation quarks at the CERN LHCrdquo Physical Review D vol 78Article ID 075018 2008
[20] I T Cakır H D Yıldız O Cakır and G Unel ldquoAnomalousresonant production of the fourth-family up-type quarks at theLHCrdquo Physical Review D vol 80 Article ID 095009 2009
[21] M Sahin S Sultansoy and S Turkoz ldquoSearching for the fourthfamily quarks through anomalous decaysrdquo Physical Review Dvol 82 no 5 Article ID 051503 2010
[22] M Bobrowski A Lenz J Riedl and J Rohrwild ldquoHow muchspace is left for a new family of fermionsrdquo Physical Review Dvol 79 no 11 Article ID 113006 15 pages 2009
[23] G Eilam B Melic and J Trampetic ldquo119862119875 violation and thefourth generationrdquo Physical Review D vol 80 no 11 Article ID116003 2009
[24] O Cobanoglu E Ozcan S Sultansoy and G Unel ldquoOPUCEMa library with error checkingmechanism for computing obliqueparametersrdquo Computer Physics Communications vol 182 no 8pp 1732ndash1743 2011
[25] T Han and J L Hewett ldquoTop-charm associated production inhigh energy 119890+119890minus collisionsrdquo Physical Review D vol 60 ArticleID 074015 1999
[26] A Belyaev N D Christensen and A Pukhov ldquoCalcHEP 34for collider physics within and beyond the standard modelrdquoComputer Physics Communications vol 184 no 7 pp 1729ndash1769 2013
[27] J Pumplin D Robert Stump J Huston H-L Lai P Nadolskyand W-K Tung ldquoNew generation of Parton distributions withuncertainties from global QCD analysisrdquo Journal of High EnergyPhysics vol 2002 article 012 2002
[28] G L Bayatian S Chatrchyan G Hmayakyan et al ldquoCMSphysics technical design report volume II physics perfor-mancerdquo Journal of Physics G Nuclear and Particle Physics vol34 no 6 p 995 2007
[29] T Sjostrand S Mrenna and P Skands ldquoPYTHIA 64 physicsand manualrdquo Journal of High Energy Physics vol 2006 no 5 p026 2006
[30] J Conway R Culbertson and R Demina Pretty Good Sim-ulation (PGS4) httpwwwphysicsucdavisedusimconwayresearchsoftwarepgspgs4-generalhtm
14 Advances in High Energy Physics
[31] EXROOTANALYSIS package for PGS4 data analysishttpmadgraphhepuiuceduDownloadsExRootAnalysis
[32] R Brun et al An object oriented data analysis framework(ROOT) httpsrootcernchdrupal
[33] F del Aguila and J A Aguilar-Saavedra ldquoMultilepton produc-tion via top flavour-changing neutral couplings at the CERNLHCrdquo Nuclear Physics B vol 576 pp 56ndash84 2000
[34] T Han M Hosch K Whisnant B-L Young and X ZhangldquoSingle top quark production via FCNC couplings at hadroncollidersrdquo Physical Review D vol 58 Article ID 073008 1998
[35] T Stelzer Z Sullivan and S Willenbrock ldquoSingle-top-quarkproduction at hadron collidersrdquoPhysical ReviewD vol 58 no 9Article ID 094021 11 pages 1998
Table 5The cross sections (in pb) of new heavy quark 1199051015840 production without cuts for PI PII and PIII parametrizations at the center of massenergy 13TeV (8TeV) respectively
Mass (GeV) PI PII PIIIradic119904 = 13 TeV (8 TeV) radic119904 = 13 TeV (8 TeV) radic119904 = 13 TeV (8 TeV)
Figure 3The cross section for the process119901119901 rarr 119887119881+119883 dependingon the new heavy quark mass for parameter sets PI PII and PII atthe center of mass energyradic119904 = 13TeV
contribution We consider that the 119882 boson decays intolepton + missing transverse momentum with the branchingratio of 21 and 119885 boson decays into dilepton with thebranching ratio of 67 In our analyses we consider the 1199051015840signal in the 119897 + 119887jet + 120574 + MET 119897 + 119887jet + 119895 + MET and3119897 + 119887jet +MET channels where 119897 = 119890 120583 However if one takesthe hadronic119882 decay the signal will be enhanced by a factorof BR(119882 rarr hadrons)BR(119882 rarr 119897])
We have obtained the cross sections by using the cutspseudorapidity |120578
119895120574| lt 25 and transverse momentum 119901
119895120574
119879gt
20ndash200GeV for jets and photon in Table 7 (Tables 8 and 9)
500 600 700 800 900 100010minus6
10minus5
10minus4
10minus3
10minus2
10minus1
100
d120590d
mtV
(pb
GeV
)
MtV (GeV)
pp rarr tg + X
pp rarr tZ + X
pp rarr t120574 + X
Figure 4 Invariant mass distributions 119898119905119881
(where 119881 = 120574 119892 and119885) for PI parametrization of the signal with 120581Λ = 02TeVminus1 and1198981199051015840 = 700GeV at the center of mass energy radic119904 = 13TeV
for PI (PII PIII) parametrization respectively Invariantmassdistribution of the 119905119881 (where 119881 = 120574 119892 and 119885) system isshown in Figure 4 for PI parametrization of the signal with120581Λ = 02TeVminus1 and 119898
1199051015840 = 700GeV at the center of mass
energy radic119904 = 13TeV It appears from signal significance cal-culations that the optimized transverse momentum cut is119901119895120574
119879gt 100GeV for 1199051015840 analysesThe backgrounds for the final state119882+119887(119887)119881 (where 119881 equiv
photon jet and 119885 boson) are given in Table 10 We apply thefollowing cuts to the final state photon and jets as |120578
119895120574| lt 25
and 119901119895120574119879
gt 20ndash200GeV For the background cross section
Advances in High Energy Physics 5
Table 6The cross sections (in pb) of new heavy quark 1198871015840 production without cuts for PI PII and PIII parametrizations at the center of massenergy of 13TeV (8TeV) respectively
Mass (GeV) PI PII PIIIradic119904 = 13 TeV (8 TeV) radic119904 = 13 TeV (8 TeV) radic119904 = 13 TeV (8 TeV)
Table 7 The cross sections (in pb) for 1199051015840 signal in different decay channels for PI parametrization with 119901119879cuts on the jets and photon and
|120578119895120574| lt 25 at the center of mass energyradic119904 = 13TeV
SignalMass (GeV)
PI119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119882+119887120574 + 119883
500 289 times 10minus1
210 times 10minus1
124 times 10minus1
102 times 10minus4
600 243 times 10minus1
164 times 10minus1
119 times 10minus1
123 times 10minus2
700 168 times 10minus1
12 times 10minus1
112 times 10minus1
225 times 10minus2
800 130 times 10minus1
103 times 10minus1
753 times 10minus2
325 times 10minus2
900 102 times 10minus1
808 times 10minus2
696 times 10minus2
302 times 10minus2
1000 761 times 10minus2
635 times 10minus2
507 times 10minus2
294 times 10minus2
119901119901 rarr 119882+119887119892 + 119883
500 778 times 100
602 times 100
363 times 100
474 times 10minus3
600 630 times 100
518 times 100
313 times 100
258 times 10minus1
700 499 times 100
363 times 100
304 times 100
932 times 10minus1
800 401 times 100
345 times 100
276 times 100
991 times 10minus1
900 332 times 100
277 times 100
213 times 100
108 times 100
1000 258 times 100
227 times 100
188 times 100
101 times 100
119901119901 rarr 119882+119887119885+119883
500 796 times 10minus1
601 times 10minus1
301 times 10minus1
101 times 10minus4
600 479 times 10minus1
386 times 10minus1
245 times 10minus1
271 times 10minus3
700 399 times 10minus1
312 times 10minus1
239 times 10minus1
696 times 10minus2
800 331 times 10minus1
289 times 10minus1
209 times 10minus1
805 times 10minus2
900 273 times 10minus1
273 times 10minus1
191 times 10minus1
954 times 10minus2
1000 223 times 10minus1
202 times 10minus1
161 times 10minus1
910 times 10minus2
estimates we assume the efficiency for 119887-tagging to be 120576119887=
50 and the rejection ratios to be 10 for 119888 (119888) quark jets and1 for light quark jets since they are assumed to bemistaggedas 119887-jets
In order to find the discovery limits we use the statisticalsignificance [28] defined as
where 119878 and 119861 are the numbers of the signal and backgroundevents respectively In Figures 5ndash7 the integrated luminosityrequired to reach 3120590 significance for the signal of 1199051015840 anoma-lous interactions is shown for parametrizations PI PII andPIII at the LHC with radic119904 = 13 TeV It is seen from these
figures that the channel 1199051015840 rarr 119905119885 requires more integratedluminosity than the other channels By requiring the signalsignificance 119878119878 = 3 the contour plots of 120581Λ and mass of1199051015840 quark are presented in Figure 8 The results show that onecan discover the 1199051015840 quark anomalous couplings 120581Λ down to01 TeVminus1 in the 119905119892 channel for119898
1199051015840 = 750GeV
411 Simulation for 1199051015840 Signal In order to include detectoreffects in the simulation we have generated 119905119881 (where 119881 =
120574 119892 and 119885) signal events for each subprocess and they aremixed using the ldquoevent mixerrdquo script which can be foundwithin the CALCHEP package [26] For further decay andhadronization these events are passed to PYTHIA [29] andsimulated with the PGS4 program [30] using generic LHC
6 Advances in High Energy Physics
Table 8 The same as Table 7 but for parametrization PII
SignalMass (GeV)
PII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119882+119887120574 + 119883
500 678 times 10minus3
507 times 10minus3
345 times 10minus3
264 times 10minus7
600 657 times 10minus3
542 times 10minus3
347 times 10minus3
534 times 10minus4
700 502 times 10minus3
431 times 10minus3
304 times 10minus3
873 times 10minus4
800 391 times 10minus3
376 times 10minus3
256 times 10minus3
103 times 10minus3
900 303 times 10minus3
268 times 10minus3
211 times 10minus3
101 times 10minus3
1000 240 times 10minus3
243 times 10minus3
177 times 10minus3
998 times 10minus4
119901119901 rarr 119882+119887119892 + 119883
500 347 times 10minus1
268 times 10minus1
152 times 10minus1
530 times 10minus6
600 251 times 10minus1
212 times 10minus1
135 times 10minus1
201 times 10minus2
700 187 times 10minus1
16 times 10minus1
116 times 10minus1
342 times 10minus2
800 146 times 10minus1
125 times 10minus1
939 times 10minus2
403 times 10minus2
900 112 times 10minus1
108 times 10minus1
780 times 10minus2
386 times 10minus2
1000 935 times 10minus2
837 times 10minus2
662 times 10minus2
368 times 10minus2
119901119901 rarr 119882+119887119885+119883
500 210 times 10minus2
177 times 10minus2
116 times 10minus2
264 times 10minus7
600 195 times 10minus2
175 times 10minus2
114 times 10minus2
134 times 10minus3
700 173 times 10minus2
143 times 10minus2
100 times 10minus2
29 times 10minus3
800 134 times 10minus2
119 times 10minus2
889 times 10minus3
342 times 10minus3
900 106 times 10minus2
955 times 10minus3
763 times 10minus3
337 times 10minus3
1000 809 times 10minus3
758 times 10minus3
631 times 10minus3
323 times 10minus3
Table 9 The same as Table 7 but for parametrization PIII
SignalMass (GeV)
PIII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119882+119887120574 + 119883
500 260 times 10minus1
278 times 10minus1
108 times 10minus1
159 times 10minus4
600 178 times 10minus1
161 times 10minus1
101 times 10minus1
142 times 10minus2
700 156 times 10minus1
135 times 10minus1
933 times 10minus2
272 times 10minus2
800 117 times 10minus1
106 times 10minus1
784 times 10minus2
332 times 10minus2
900 904 times 10minus2
842 times 10minus2
668 times 10minus2
325 times 10minus2
1000 760 times 10minus2
676 times 10minus2
516 times 10minus2
317 times 10minus2
119901119901 rarr 119882+119887119892 + 119883
500 839 times 100
649 times 100
386 times 100
465 times 10minus3
600 610 times 100
578 times 100
381 times 100
556 times 10minus1
700 539 times 100
464 times 100
341 times 100
970 times 10minus1
800 394 times 100
354 times 100
273 times 100
105 times 100
900 324 times 100
276 times 100
227 times 100
107 times 100
1000 233 times 100
229 times 100
184 times 100
998 times 10minus1
119901119901 rarr 119882+119887119885+119883
500 772 times 10minus1
101 times 100
217 times 10minus1
627 times 10minus4
600 624 times 10minus1
385 times 10minus1
292 times 10minus1
320 times 10minus2
700 500 times 10minus1
305 times 10minus1
286 times 10minus1
580 times 10minus2
800 378 times 10minus1
250 times 10minus1
242 times 10minus1
964 times 10minus2
900 304 times 10minus1
167 times 10minus1
206 times 10minus1
962 times 10minus2
1000 251 times 10minus1
129 times 10minus1
148 times 10minus1
961 times 10minus2
Advances in High Energy Physics 7
Table 10The cross sections (in pb) for the relevant backgrounds (119882+119887(119887)119881119882+119888(119888)119881 and119882+119895119881 where119881 = photon jet and119885 boson) with119901119879cuts on the jets at the center of mass energyradic119904 = 13TeV
Background 119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119882+119887120574 + 119883 237 times 10
minus3362 times 10
minus4617 times 10
minus5699 times 10
minus6
119901119901 rarr 119882+119888120574 + 119883 415 times 10
0459 times 10
minus1625 times 10
minus2621 times 10
minus3
119901119901 rarr 119882+119895120574 + 119883 263 times 10
1430 times 10
0733 times 10
minus1127 times 10
minus1
119901119901 rarr 119882+119887(119887)119895 + 119883 726 times 10
1302 times 10
1611 times 10
0974 times 10
minus1
119901119901 rarr 119882+119888(119888)119895 + 119883 598 times 10
2965 times 10
1179 times 10
1242 times 10
0
119901119901 rarr 119882+119895119895 + 119883 731 times 10
3778 times 10
2161 times 10
2258 times 10
1
119901119901 rarr 119882+119887119885 + 119883 626 times 10
minus4399 times 10
minus4193 times 10
minus4471 times 10
minus5
119901119901 rarr 119882+119888119885 + 119883 529 times 10
minus1340 times 10
minus1166 times 10
minus1415 times 10
minus2
119901119901 rarr 119882+119895119885 + 119883 859 times 10
0483 times 10
0249 times 10
0791 times 10
minus1
500 600 700 800 900 100010minus2
10minus1
100
101
102
103
t998400 rarr tZ
t998400 rarr t120574
t998400 rarr tg
Mt998400 (GeV)
Lin
t(fb
minus1)
Figure 5 Integrated luminosity required to reach 3120590 significancefor the signal of 1199051015840 anomalous interactions for parametrization PI atthe LHC withradic119904 = 13TeV
102
103
104
500 600 700 800 900 1000
t998400 rarr tZ
t998400 rarr t120574
t998400 rarr tg
Mt998400 (GeV)
Lin
t(fb
minus1)
Figure 6 The same as Figure 5 but for parametrization PII
500 600 700 800 900 100010minus2
10minus1
100
101
102
103
t998400 rarr tZ
t998400 rarr t120574
t998400 rarr tg
Mt998400 (GeV)
Lin
t(fb
minus1)
Figure 7 The same as Figure 5 but for parametrization PIII
detector parametersThis fast simulation includes the impor-tant detector effects such as tracking smearing effects of thecalorimeters resolution and tag efficiencies The EXROOT-ANALYSIS package [31] is used for the simulated events andthe output is analyzed and histogrammed with the ROOT[32] macros We consider jets (up to five) leptons (electronsor muons) photons and missing transverse momentumwithin the simulated events for the 119905120574 119905119895 and 119905119885 eventsgeneration The typical kinematical distributions are shownin Figures 9-10
In the analysis the signal (with 120581Λ = 02TeVminus1 and1198981199051015840 = 700GeV) and the corresponding background (119882119895119881)
are taken into accountThe 119904-channel contribution to the sig-nal process appears as a resonance around the 1199051015840mass value inthe reconstructed invariant mass 119898rec
1199051015840 The reconstructed
mass distribution for the 1199051015840 signal (reconstructed from a topquark and a vector boson) is shown in Figure 11
Similar to the single top processes the top quark in thefinal state is reconstructed from a leading jet (commonly 119887jet)and a119882 boson (which can be reconstructed from its leptonicor hadronic decay) For the 119905120574 production we require
8 Advances in High Energy Physics
500 600 700 800 900 1000
Mt998400 (GeV)
01
02
03
04
05120581Λ
(TeV
minus1 )
t998400 rarr WbZ
t998400 rarr Wb120574
t998400 rarr Wbg
Figure 8The contour plot of anomalous coupling and mass of newheavy quark 1199051015840 for the dynamical parametrization explained in thetext with a significance of 3120590 atradic119904 = 13TeV and 119871 int = 100fb
minus1
50 100 150 200 250 300 350 400
Entr
ies
0
2000
4000
6000
8000
10000
12000
14000
16000
PhotonJet 1
Jet 2Jet 3
pT (GeV)
Figure 9 Transverse momentum distributions of leading jet (Jet 1)and other jets (Jet 2 and Jet 3) and photon for signal (119905120574 production)after detector simulation
systematically the large transverse momentum of photon(119901120574119879gt 100GeV) minimum jet transverse momentum (119901119895
119879gt
20GeV) and the pseudorapidity range (|120578119895120574| lt 25) inaddition to the requirements on mass reconstruction of119882-boson and top quark The large 119901120574
119879and the requirement of
single 119887-tagging allow a better separation of the signal (for 119905120574channel) from the background Other channels for 119905119892 and 119905119885productions are more challenging due to a large number ofjets which require additional discriminators such as angularandor total transverse energy variables However in orderto get rid of the backgrounds from 119882119905 and 119905119905 production
Entr
ies
50 100 150 200 250 300 350 4000
5000
10000
15000
20000
25000
PhotonJet 1
Jet 2Jet 3
pT (GeV)
Figure 10 Transverse momentum distributions of leading jet (Jet1) and other jets (Jet 2 and Jet 3) and photon for background (119882119895120574production)
500 600 700 800 900 1000
40
60
80
100
120
BackgroundSignal
Mrect998400
(GeV)
Even
ts10
GeV
Figure 11The reconstructedmass distributions for background andsignal (119905120574) with119898
1199051015840 = 700GeV and 120581Λ = 015TeVminus1
(for a similar framework the production cross sections areabout 25 pb and 340 pb resp) one can consider the channel3119897 + 119887jet + MET for a distinctive signal from the 1199051015840 rarr 119905119885An analysis of the investigation of single top production withsimilar backgrounds at the LHC can be found in [33ndash35]
42 Analysis of the Process 119901119901 rarr 119887119881 + 119883 (119881 = 119892 119885 120574) for1198871015840 Signal The signal process 119901119901 rarr 119887119881 + 119883 (119881 = 119892 119885 120574)includes the new heavy quark 1198871015840 exchange in both the 119904-channel and the 119905-channel The 119904-channel contributes to thesignal process as resonance around the 1198871015840mass value in the 119887119881invariantmass while the 119905-channel contributes to the nonres-onant behaviour For this process we consider the leptonicdecay of 119885 boson In the analyses we consider the 1198871015840 signalto be 119887jet + 120574 119887jet + 119895 and 119887jet + dilepton
Advances in High Energy Physics 9
Table 11 The cross sections (in pb) for 1198871015840 signal in different decay channel for parametrization PI with 119901119879cuts on the jets and photon and
|120578119895120574| lt 25 at the center of mass energyradic119904 = 13TeV
SignalMass (GeV)
PI119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887120574 + 119883
500 564 times 10minus2
562 times 10minus2
549 times 10minus2
395 times 10minus2
600 396 times 10minus2
396 times 10minus2
390 times 10minus2
333 times 10minus2
700 287 times 10minus2
287 times 10minus2
286 times 10minus2
259 times 10minus2
800 212 times 10minus2
213 times 10minus2
212 times 10minus2
199 times 10minus2
900 160 times 10minus2
160 times 10minus2
160 times 10minus2
153 times 10minus2
1000 122 times 10minus2
122 times 10minus2
122 times 10minus2
119 times 10minus2
119901119901 rarr 119887119892 + 119883
500 813 times 100
813 times 100
793 times 100
596 times 100
600 559 times 100
559 times 100
553 times 100
488 times 100
700 398 times 100
398 times 100
396 times 100
373 times 100
800 291 times 100
291 times 100
290 times 100
281 times 100
900 216 times 100
216 times 100
216 times 100
214 times 100
1000 164 times 100
163 times 100
163 times 100
162 times 100
119901119901 rarr 119887119885 + 119883
500 787 times 10minus1
781 times 10minus1
750 times 10minus1
479 times 10minus1
600 548 times 10minus1
548 times 10minus1
531 times 10minus1
427 times 10minus1
700 395 times 10minus1
394 times 10minus1
386 times 10minus1
339 times 10minus1
800 292 times 10minus1
291 times 10minus1
286 times 10minus1
261 times 10minus1
900 218 times 10minus1
218 times 10minus1
215 times 10minus1
202 times 10minus1
1000 166 times 10minus1
166 times 10minus1
164 times 10minus1
156 times 10minus1
We have obtained the cross sections by using the pseu-dorapidity cuts |120578
119895120574| lt 25 and transverse momentum cuts
119901119895120574
119879gt 20ndash200GeV for jets and photon in Table 11 (Tables
12 and 13) for PI (PII PIII) parametrizations respectivelyInvariantmass distribution of the 119887119881 (where119881 = 120574 119892 and119885)system is shown in Figure 12 for PI parametrization of thesignal with 120581Λ = 02TeVminus1 and 119898
1198871015840 = 700GeV at the
center of mass energy radic119904 = 13TeV It appears from sig-nal significance calculation that the optimized transversemomentum cut is 119901
119879gt 200GeV for 1198871015840 analyses
The backgrounds for the final state 119887(119887)119881 (where 119881 equiv
photon jet and 119885 boson) are given in Table 14 We apply thefollowing cuts to the final state photon and jets as |120578
119895120574| lt 25
and 119901119895120574119879gt 20ndash200GeV It can be noted that the background
cross section decreases as the119901119879cuts increaseWe assume the
efficiency for 119887-tagging to be 120576119887= 50and the rejection ratios
to be 10 for 119888 (119888) quark jets and 1 for light quark jetsIn order to reach 3120590 significance for the signal of 1198871015840
anomalous interactions the required integrated luminosityis shown in Figures 13ndash15 for parametrizations PI PII andPIII at the LHC with radic119904 = 13TeV The channel 1198871015840 rarr 119887120574
requires more integrated luminosity than the other channelsBy requiring the signal significance 119878119878 = 3 the contour plotsof 120581Λ and mass of 1198871015840 quark are presented in Figure 16 Theresults show that one can discover the 1198871015840 quark anomalouscouplings down to 01 in the 119887119892 channel for119898
1198871015840 = 500GeV
500 600 700 800 900 100010minus6
10minus5
10minus4
10minus3
10minus2
10minus1
100
d120590d
mbV
(pb
GeV
)
MbV (GeV)
pp rarr bg + X
pprarr bZ + X
pprarr b120574 + X
Figure 12 Invariant mass distribution of the 119887119881 (where 119881 = 120574 119892and 119885) system is shown in Figure 5 for PI parametrization of thesignal with 120581Λ = 02TeVminus1 and 119898
1198871015840 = 700GeV at the center of
mass energyradic119904 = 13TeV
421 Simulation for 1198871015840 Signal In the simulation we havegenerated 119887119881 (where 119881 = 120574 119892 and 119885) events for each sub-process and these events are simulated using generic detector
10 Advances in High Energy Physics
Table 12 The same as Table 11 but for parametrization PII
SignalMass (GeV)
PII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887120574 + 119883
500 518 times 10minus3
526 times 10minus3
504 times 10minus3
354 times 10minus3
600 338 times 10minus3
337 times 10minus3
336 times 10minus3
277 times 10minus3
700 232 times 10minus3
231 times 10minus3
230 times 10minus3
205 times 10minus3
800 171 times 10minus3
163 times 10minus3
164 times 10minus3
150 times 10minus3
900 117 times 10minus3
116 times 10minus3
117 times 10minus3
111 times 10minus3
1000 860 times 10minus4
858 times 10minus4
855 times 10minus4
824 times 10minus4
119901119901 rarr 119887119892 + 119883
500 740 times 10minus1
739 times 10minus1
721 times 10minus1
516 times 10minus1
600 483 times 10minus1
480 times 10minus1
481 times 10minus1
398 times 10minus1
700 322 times 10minus1
322 times 10minus1
320 times 10minus1
289 times 10minus1
800 224 times 10minus1
221 times 10minus1
221 times 10minus1
204 times 10minus1
900 15 times 10minus1
158 times 10minus1
158 times 10minus1
149 times 10minus1
1000 114 times 10minus1
114 times 10minus1
113 times 10minus1
110 times 10minus1
119901119901 rarr 119887119885 + 119883
500 689 times 10minus2
685 times 10minus2
645 times 10minus2
423 times 10minus2
600 452 times 10minus2
451 times 10minus2
434 times 10minus2
353 times 10minus2
700 312 times 10minus2
311 times 10minus2
305 times 10minus2
265 times 10minus2
800 219 times 10minus2
218 times 10minus2
215 times 10minus2
195 times 10minus2
900 156 times 10minus2
156 times 10minus2
155 times 10minus2
144 times 10minus2
1000 114 times 10minus2
113 times 10minus2
113 times 10minus2
107 times 10minus2
Table 13 The same as Table 11 but for parametrization PIII
SignalMass (GeV)
PIII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887120574 + 119883
500 131 times 10minus2
1314 times 10minus2
1275 times 10minus2
892 times 10minus2
600 859 times 10minus2
858 times 10minus2
844 times 10minus2
703 times 10minus2
700 582 times 10minus2
582 times 10minus2
577 times 10minus2
517 times 10minus2
800 407 times 10minus2
407 times 10minus2
406 times 10minus2
377 times 10minus2
900 292 times 10minus2
292 times 10minus2
291 times 10minus2
277 times 10minus2
1000 214 times 10minus2
213 times 10minus2
213 times 10minus2
206 times 10minus2
119901119901 rarr 119887119892 + 119883
500 1904 times 100
1896 times 100
1843 times 100
1286 times 100
600 1219 times 100
1213 times 100
1193 times 100
992 times 100
700 808 times 100
807 times 100
802 times 100
717 times 100
800 557 times 100
557 times 100
555 times 100
515 times 100
900 394 times 100
394 times 100
394 times 100
374 times 100
1000 285 times 100
285 times 100
285 times 100
274 times 100
119901119901 rarr 119887119885 + 119883
500 176 times 100
175 times 100
165 times 100
105 times 100
600 115 times 100
114 times 100
111 times 100
880 times 10minus1
700 783 times 10minus1
780 times 10minus1
760 times 10minus1
661 times 10minus1
800 547 times 10minus1
541 times 10minus1
531 times 10minus1
480 times 10minus1
900 392 times 10minus1
390 times 10minus1
382 times 10minus1
360 times 10minus1
1000 286 times 10minus1
282 times 10minus1
280 times 10minus1
262 times 10minus1
Advances in High Energy Physics 11
Table 14 The cross sections (in pb) for the backgrounds (119887(119887)119881 119888(119888)119881 and 119895119881 where119881 = photon jet and 119885 boson) with 119901119879cuts on the jets
and photon at the center of mass energy radic119904 = 13TeV
Background 119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887(119887)120574 + 119883 299 times 103
135 times 102
904 times 100
402 times 10minus1
119901119901 rarr 119888(119888)120574 + 119883 187 times 104
815 times 102
540 times 101
243 times 100
119901119901 rarr 119895120574 + 119883 543 times 104
327 times 103
338 times 102
285 times 101
119901119901 rarr 119887(119887)119895 + 119883 783 times 106
305 times 105
192 times 104
893 times 102
119901119901 rarr 119888(119888)119895 + 119883 122 times 107
455 times 105
289 times 104
135 times 103
119901119901 rarr 119895119895 + 119883 243 times 108
854 times 106
544 times 105
280 times 104
119901119901 rarr 119887(119887)119885 + 119883 502 times 102
135 times 102
225 times 101
156 times 100
119901119901 rarr 119888(119888)119885 + 119883 596 times 102
158 times 102
264 times 101
183 times 100
119901119901 rarr 119895119885 + 119883 800 times 103
208 times 103
408 times 102
412 times 101
500 600 700 800 900 1000
Mb998400 (GeV)
10minus1
100
101
102
103
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Figure 13 Integrated luminosity required to reach 3120590 significancefor the signal of 1198871015840 anomalous interactions for parametrization PI atthe LHC withradic119904 = 13TeV
500 600 700 800 900 1000
Mb998400 (GeV)
104
101
102
103
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Figure 14 The same as Figure 13 but for parametrization PII
500 600 700 800 900 100010minus1
100
101
102
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Mb998400 (GeV)
Figure 15 The same as Figure 13 but for parametrization PIII
parameters to include detector effects such as tracking tag-ging efficiencies and smearing effects After the simulationthe typical kinematical distributions are shown in Figures 17-18
In the analysis the signal (with 120581Λ = 03TeVminus1 and1198981198871015840 = 700GeV) and the corresponding background are
taken into account The invariant mass of the new heavyquark 1198871015840 can be reconstructed from a 119887jet and a neutral gaugeboson (where the 119885 boson can also be reconstructed fromits dilepton or hadronic decay) For the 119887120574 production werequire a large 119901120574
119879(gt100GeV) for photon and large 119901119895
119879
(gt100GeV) for jet and pseudorapidity |120578119895120574| (lt25) For the 119887120574signal channel the invariantmass distributions for signal andbackground events are shown in Figure 19The large 119901119895120574
119879and
the requirement of single 119887-tagging allow a better separationof the signal (for 119887120574 channel) from the background and thenwe find a precise limit for the anomalous coupling in thischannel For the 119887119892 and 119887119885 production we require two high119901119879jets (one 119887-jet) and a high 119901
119879jet in addition to the
reconstructed mass 119898rec119885 respectively The main character of
12 Advances in High Energy Physics
500 600 700 800 900 100001
02
03
04
05120581Λ
(TeV
minus1 )
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Mb998400 (GeV)
Figure 16The contour plot of anomalous coupling andmass of newheavy quark 1198871015840 for the dynamical parametrization explained in thetext with a significance of 3120590 atradic119904 = 13TeV and 119871 int = 100fb
minus1
50 100 150 200 250 300 350 400
Entr
ies
0
2000
4000
6000
8000
10000
PhotonJet 1
pT (GeV)
Figure 17 Transverse momentum distributions of leading jet andphoton (119887120574 production) for signal after detector simulation
the signal is the high 119901119895119879andor 119901120574
119879and single 119887-tagged jet
We calculate the signal and background events in the range|119898
rec1198871015840 (GeV) minus 700GeV| lt 50GeV and we find a similar
significance as shown in Figure 16
5 Conclusion
The new heavy quarks of up-type and down-type can be pro-duced with large numbers at the LHC if they have the anoma-lous couplings (via flavor changing neutral current) thatwell dominate over the charged current interactions The
Entr
ies
50 100 150 200 250 300 350 4000
2000
4000
6000
8000
10000
12000
PhotonJet 1
pT (GeV)
Figure 18 Transverse momentum distributions of leading jet andphoton (119895120574 production) for background at the given conditionsmentioned in the text
500 550 600 650 700 750 800 850 900 950 10000
500
1000
1500
2000
2500
3000
BackgroundSignal
Mrecb998400
(GeV)
Even
ts10
GeV
Figure 19The reconstructedmass distributions for background andsignal (119887120574) with119898
1198871015840 = 700GeV and 120581Λ = 03TeVminus1
single production of new heavy quarks can be achievedthrough the anomalous interactions at the LHC with radic119904 =13TeV The anomalous vertices could appear significantly atleading order processes due to the possibility of new heavyquarks From the results of signal significance calculationsfor 1199051015840 (1198871015840) anomalous productions the sensitivity to theanomalous couplings 120581119905
1015840
Λ (1205811198871015840
Λ) can be reached down to010 TeVminus1 (015 TeVminus1) in the lepton + 119887jet + jet +MET (119887jet +jet) channel at radic119904 = 13TeV assuming a dynamical para-metrization for the anomalous couplings and the mass of 750GeV for the new heavy quarks The observability limits onthe anomalous couplings obtained after the simulation arecomparable with the partonic level analysis in the photon and119885 boson associated channels whereas the productions 119905119892 and119887119892 are less comparable due to the fast simulation method In
Advances in High Energy Physics 13
any case the single 119887 tagging will play an important role inprobing new heavy quarks and reducing the background
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgment
This work was supported in part by Turkish Atomic EnergyAuthority (TAEA) under Project Grant no 2011TAEKCERN-A5H2P101-19
References
[1] H J He N Polonsky and S F Su ldquoExtra families Higgs spec-trum and oblique correctionsrdquo Physical Review D vol 64 no5 Article ID 053004 11 pages 2001
[2] B Holdom W S Hou T Hurth M L Mangano S Sultansoyand G Unel ldquoFour statements about the fourth generationrdquoPMC Physics A vol 3 article 4 2009
[3] A Atre M Carena T Han and J Santiago ldquoHeavy quarksabove the top at the Tevatronrdquo Physical ReviewD vol 79 ArticleID 054018 2009
[4] A Atre G Azuelos M Carena et al ldquoModel-independentsearches for new quarks at the LHCrdquo Journal of High EnergyPhysics vol 2011 no 8 article 080 2011
[5] N Chen and H J He ldquoLHC signatures of two-Higgs-doubletswith fourth familyrdquo Journal of High Energy Physics vol 2012article 062 2012
[6] M S Chanowitz ldquoElectroweak constraints on the fourth gener-ation at two loop orderrdquo Physical Review D vol 88 Article ID015012 2013
[7] S Chakdar K Ghosh S Nandi and S K Rai ldquoCollider signa-tures of mirror fermions in the framework of a left-right mirrormodelrdquo Physical Review D vol 88 Article ID 095005 2013
[8] X F Wang C Du and H J He ldquoLHC Higgs signatures fromtopflavor seesaw mechanismrdquo Physics Letters B vol 723 no 4-5 pp 314ndash323 2013
[9] S Bar-Shalom M Geller S Nandi and A Soni ldquoTwo higgsdoublets a 4th generation and a 125GeV higgs a reviewrdquoAdvances in High Energy Physics vol 2013 Article ID 67297228 pages 2013
[10] H Fritzsch and D Holtmannspotter ldquoThe production of singlet-quarks at LEP and HERArdquo Physics Letters B vol 457 no 1ndash3pp 186ndash192 1999
[11] G Aad B Abbott J Abdallah et al ldquoSearch for down-typefourth generation quarks with the ATLAS detector in eventswith one lepton and hadronically decaying119882 bosonsrdquo PhysicalReview Letters vol 109 Article ID 032001 2012
[12] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoSearchfor pair produced fourth-generation up-type quarks in ppcollisions atradic119904 = 7 TeV with a lepton in the final staterdquo PhysicsLetters B vol 718 pp 307ndash328 2012
[13] G Aad B Abbott J Abdallah et al ldquoSearch for pair and singleproduction of new heavy quarks that decay to a Z boson and athird-generation quark in pp collisions at radic119904 = 8TeV with theATLAS detectorrdquo Journal of High Energy Physics vol 2014 no11 article 104 2014
[14] G Aad T Abajyan B Abbott et al ldquoSearch for pair productionof heavy top-like quarks decaying to a high-pTW boson and ab quark in the lepton plus jets final state at radic119904 = 7TeV with theATLAS detectorrdquo Physics Letters B vol 718 no 4ndash5 pp 1284ndash1302 2013
[15] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoSearchfor heavy top-like quark pair production in the dilepton finalstate in pp collisions at radic119904 = 7TeVrdquo Physics Letters B vol 716no 1 pp 103ndash121 2012
[16] G Aad B Abbott J Abdallah et al ldquoSearch for heavy vector-like quarks coupling to light quarks in protonndashproton collisionsat radic119904 = 7 Tev with the ATLAS detectorrdquo Physics Letters B vol712 no 1-2 pp 22ndash39 2012
[17] G Aad T Abajyan B Abbott et al ldquoSearch for a heavy top-quark partner in final states with two leptons with the ATLASdetector at the LHCrdquo Journal of High Energy Physics vol 2012article 94 2012
[18] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoCom-bined search for the quarks of a sequential fourth generationrdquoPhysical Review D vol 86 no 11 Article ID 112003 20 pages2012
[19] R Ciftci ldquoAnomalous single production of the fourth gener-ation quarks at the CERN LHCrdquo Physical Review D vol 78Article ID 075018 2008
[20] I T Cakır H D Yıldız O Cakır and G Unel ldquoAnomalousresonant production of the fourth-family up-type quarks at theLHCrdquo Physical Review D vol 80 Article ID 095009 2009
[21] M Sahin S Sultansoy and S Turkoz ldquoSearching for the fourthfamily quarks through anomalous decaysrdquo Physical Review Dvol 82 no 5 Article ID 051503 2010
[22] M Bobrowski A Lenz J Riedl and J Rohrwild ldquoHow muchspace is left for a new family of fermionsrdquo Physical Review Dvol 79 no 11 Article ID 113006 15 pages 2009
[23] G Eilam B Melic and J Trampetic ldquo119862119875 violation and thefourth generationrdquo Physical Review D vol 80 no 11 Article ID116003 2009
[24] O Cobanoglu E Ozcan S Sultansoy and G Unel ldquoOPUCEMa library with error checkingmechanism for computing obliqueparametersrdquo Computer Physics Communications vol 182 no 8pp 1732ndash1743 2011
[25] T Han and J L Hewett ldquoTop-charm associated production inhigh energy 119890+119890minus collisionsrdquo Physical Review D vol 60 ArticleID 074015 1999
[26] A Belyaev N D Christensen and A Pukhov ldquoCalcHEP 34for collider physics within and beyond the standard modelrdquoComputer Physics Communications vol 184 no 7 pp 1729ndash1769 2013
[27] J Pumplin D Robert Stump J Huston H-L Lai P Nadolskyand W-K Tung ldquoNew generation of Parton distributions withuncertainties from global QCD analysisrdquo Journal of High EnergyPhysics vol 2002 article 012 2002
[28] G L Bayatian S Chatrchyan G Hmayakyan et al ldquoCMSphysics technical design report volume II physics perfor-mancerdquo Journal of Physics G Nuclear and Particle Physics vol34 no 6 p 995 2007
[29] T Sjostrand S Mrenna and P Skands ldquoPYTHIA 64 physicsand manualrdquo Journal of High Energy Physics vol 2006 no 5 p026 2006
[30] J Conway R Culbertson and R Demina Pretty Good Sim-ulation (PGS4) httpwwwphysicsucdavisedusimconwayresearchsoftwarepgspgs4-generalhtm
14 Advances in High Energy Physics
[31] EXROOTANALYSIS package for PGS4 data analysishttpmadgraphhepuiuceduDownloadsExRootAnalysis
[32] R Brun et al An object oriented data analysis framework(ROOT) httpsrootcernchdrupal
[33] F del Aguila and J A Aguilar-Saavedra ldquoMultilepton produc-tion via top flavour-changing neutral couplings at the CERNLHCrdquo Nuclear Physics B vol 576 pp 56ndash84 2000
[34] T Han M Hosch K Whisnant B-L Young and X ZhangldquoSingle top quark production via FCNC couplings at hadroncollidersrdquo Physical Review D vol 58 Article ID 073008 1998
[35] T Stelzer Z Sullivan and S Willenbrock ldquoSingle-top-quarkproduction at hadron collidersrdquoPhysical ReviewD vol 58 no 9Article ID 094021 11 pages 1998
Table 6The cross sections (in pb) of new heavy quark 1198871015840 production without cuts for PI PII and PIII parametrizations at the center of massenergy of 13TeV (8TeV) respectively
Mass (GeV) PI PII PIIIradic119904 = 13 TeV (8 TeV) radic119904 = 13 TeV (8 TeV) radic119904 = 13 TeV (8 TeV)
Table 7 The cross sections (in pb) for 1199051015840 signal in different decay channels for PI parametrization with 119901119879cuts on the jets and photon and
|120578119895120574| lt 25 at the center of mass energyradic119904 = 13TeV
SignalMass (GeV)
PI119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119882+119887120574 + 119883
500 289 times 10minus1
210 times 10minus1
124 times 10minus1
102 times 10minus4
600 243 times 10minus1
164 times 10minus1
119 times 10minus1
123 times 10minus2
700 168 times 10minus1
12 times 10minus1
112 times 10minus1
225 times 10minus2
800 130 times 10minus1
103 times 10minus1
753 times 10minus2
325 times 10minus2
900 102 times 10minus1
808 times 10minus2
696 times 10minus2
302 times 10minus2
1000 761 times 10minus2
635 times 10minus2
507 times 10minus2
294 times 10minus2
119901119901 rarr 119882+119887119892 + 119883
500 778 times 100
602 times 100
363 times 100
474 times 10minus3
600 630 times 100
518 times 100
313 times 100
258 times 10minus1
700 499 times 100
363 times 100
304 times 100
932 times 10minus1
800 401 times 100
345 times 100
276 times 100
991 times 10minus1
900 332 times 100
277 times 100
213 times 100
108 times 100
1000 258 times 100
227 times 100
188 times 100
101 times 100
119901119901 rarr 119882+119887119885+119883
500 796 times 10minus1
601 times 10minus1
301 times 10minus1
101 times 10minus4
600 479 times 10minus1
386 times 10minus1
245 times 10minus1
271 times 10minus3
700 399 times 10minus1
312 times 10minus1
239 times 10minus1
696 times 10minus2
800 331 times 10minus1
289 times 10minus1
209 times 10minus1
805 times 10minus2
900 273 times 10minus1
273 times 10minus1
191 times 10minus1
954 times 10minus2
1000 223 times 10minus1
202 times 10minus1
161 times 10minus1
910 times 10minus2
estimates we assume the efficiency for 119887-tagging to be 120576119887=
50 and the rejection ratios to be 10 for 119888 (119888) quark jets and1 for light quark jets since they are assumed to bemistaggedas 119887-jets
In order to find the discovery limits we use the statisticalsignificance [28] defined as
where 119878 and 119861 are the numbers of the signal and backgroundevents respectively In Figures 5ndash7 the integrated luminosityrequired to reach 3120590 significance for the signal of 1199051015840 anoma-lous interactions is shown for parametrizations PI PII andPIII at the LHC with radic119904 = 13 TeV It is seen from these
figures that the channel 1199051015840 rarr 119905119885 requires more integratedluminosity than the other channels By requiring the signalsignificance 119878119878 = 3 the contour plots of 120581Λ and mass of1199051015840 quark are presented in Figure 8 The results show that onecan discover the 1199051015840 quark anomalous couplings 120581Λ down to01 TeVminus1 in the 119905119892 channel for119898
1199051015840 = 750GeV
411 Simulation for 1199051015840 Signal In order to include detectoreffects in the simulation we have generated 119905119881 (where 119881 =
120574 119892 and 119885) signal events for each subprocess and they aremixed using the ldquoevent mixerrdquo script which can be foundwithin the CALCHEP package [26] For further decay andhadronization these events are passed to PYTHIA [29] andsimulated with the PGS4 program [30] using generic LHC
6 Advances in High Energy Physics
Table 8 The same as Table 7 but for parametrization PII
SignalMass (GeV)
PII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119882+119887120574 + 119883
500 678 times 10minus3
507 times 10minus3
345 times 10minus3
264 times 10minus7
600 657 times 10minus3
542 times 10minus3
347 times 10minus3
534 times 10minus4
700 502 times 10minus3
431 times 10minus3
304 times 10minus3
873 times 10minus4
800 391 times 10minus3
376 times 10minus3
256 times 10minus3
103 times 10minus3
900 303 times 10minus3
268 times 10minus3
211 times 10minus3
101 times 10minus3
1000 240 times 10minus3
243 times 10minus3
177 times 10minus3
998 times 10minus4
119901119901 rarr 119882+119887119892 + 119883
500 347 times 10minus1
268 times 10minus1
152 times 10minus1
530 times 10minus6
600 251 times 10minus1
212 times 10minus1
135 times 10minus1
201 times 10minus2
700 187 times 10minus1
16 times 10minus1
116 times 10minus1
342 times 10minus2
800 146 times 10minus1
125 times 10minus1
939 times 10minus2
403 times 10minus2
900 112 times 10minus1
108 times 10minus1
780 times 10minus2
386 times 10minus2
1000 935 times 10minus2
837 times 10minus2
662 times 10minus2
368 times 10minus2
119901119901 rarr 119882+119887119885+119883
500 210 times 10minus2
177 times 10minus2
116 times 10minus2
264 times 10minus7
600 195 times 10minus2
175 times 10minus2
114 times 10minus2
134 times 10minus3
700 173 times 10minus2
143 times 10minus2
100 times 10minus2
29 times 10minus3
800 134 times 10minus2
119 times 10minus2
889 times 10minus3
342 times 10minus3
900 106 times 10minus2
955 times 10minus3
763 times 10minus3
337 times 10minus3
1000 809 times 10minus3
758 times 10minus3
631 times 10minus3
323 times 10minus3
Table 9 The same as Table 7 but for parametrization PIII
SignalMass (GeV)
PIII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119882+119887120574 + 119883
500 260 times 10minus1
278 times 10minus1
108 times 10minus1
159 times 10minus4
600 178 times 10minus1
161 times 10minus1
101 times 10minus1
142 times 10minus2
700 156 times 10minus1
135 times 10minus1
933 times 10minus2
272 times 10minus2
800 117 times 10minus1
106 times 10minus1
784 times 10minus2
332 times 10minus2
900 904 times 10minus2
842 times 10minus2
668 times 10minus2
325 times 10minus2
1000 760 times 10minus2
676 times 10minus2
516 times 10minus2
317 times 10minus2
119901119901 rarr 119882+119887119892 + 119883
500 839 times 100
649 times 100
386 times 100
465 times 10minus3
600 610 times 100
578 times 100
381 times 100
556 times 10minus1
700 539 times 100
464 times 100
341 times 100
970 times 10minus1
800 394 times 100
354 times 100
273 times 100
105 times 100
900 324 times 100
276 times 100
227 times 100
107 times 100
1000 233 times 100
229 times 100
184 times 100
998 times 10minus1
119901119901 rarr 119882+119887119885+119883
500 772 times 10minus1
101 times 100
217 times 10minus1
627 times 10minus4
600 624 times 10minus1
385 times 10minus1
292 times 10minus1
320 times 10minus2
700 500 times 10minus1
305 times 10minus1
286 times 10minus1
580 times 10minus2
800 378 times 10minus1
250 times 10minus1
242 times 10minus1
964 times 10minus2
900 304 times 10minus1
167 times 10minus1
206 times 10minus1
962 times 10minus2
1000 251 times 10minus1
129 times 10minus1
148 times 10minus1
961 times 10minus2
Advances in High Energy Physics 7
Table 10The cross sections (in pb) for the relevant backgrounds (119882+119887(119887)119881119882+119888(119888)119881 and119882+119895119881 where119881 = photon jet and119885 boson) with119901119879cuts on the jets at the center of mass energyradic119904 = 13TeV
Background 119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119882+119887120574 + 119883 237 times 10
minus3362 times 10
minus4617 times 10
minus5699 times 10
minus6
119901119901 rarr 119882+119888120574 + 119883 415 times 10
0459 times 10
minus1625 times 10
minus2621 times 10
minus3
119901119901 rarr 119882+119895120574 + 119883 263 times 10
1430 times 10
0733 times 10
minus1127 times 10
minus1
119901119901 rarr 119882+119887(119887)119895 + 119883 726 times 10
1302 times 10
1611 times 10
0974 times 10
minus1
119901119901 rarr 119882+119888(119888)119895 + 119883 598 times 10
2965 times 10
1179 times 10
1242 times 10
0
119901119901 rarr 119882+119895119895 + 119883 731 times 10
3778 times 10
2161 times 10
2258 times 10
1
119901119901 rarr 119882+119887119885 + 119883 626 times 10
minus4399 times 10
minus4193 times 10
minus4471 times 10
minus5
119901119901 rarr 119882+119888119885 + 119883 529 times 10
minus1340 times 10
minus1166 times 10
minus1415 times 10
minus2
119901119901 rarr 119882+119895119885 + 119883 859 times 10
0483 times 10
0249 times 10
0791 times 10
minus1
500 600 700 800 900 100010minus2
10minus1
100
101
102
103
t998400 rarr tZ
t998400 rarr t120574
t998400 rarr tg
Mt998400 (GeV)
Lin
t(fb
minus1)
Figure 5 Integrated luminosity required to reach 3120590 significancefor the signal of 1199051015840 anomalous interactions for parametrization PI atthe LHC withradic119904 = 13TeV
102
103
104
500 600 700 800 900 1000
t998400 rarr tZ
t998400 rarr t120574
t998400 rarr tg
Mt998400 (GeV)
Lin
t(fb
minus1)
Figure 6 The same as Figure 5 but for parametrization PII
500 600 700 800 900 100010minus2
10minus1
100
101
102
103
t998400 rarr tZ
t998400 rarr t120574
t998400 rarr tg
Mt998400 (GeV)
Lin
t(fb
minus1)
Figure 7 The same as Figure 5 but for parametrization PIII
detector parametersThis fast simulation includes the impor-tant detector effects such as tracking smearing effects of thecalorimeters resolution and tag efficiencies The EXROOT-ANALYSIS package [31] is used for the simulated events andthe output is analyzed and histogrammed with the ROOT[32] macros We consider jets (up to five) leptons (electronsor muons) photons and missing transverse momentumwithin the simulated events for the 119905120574 119905119895 and 119905119885 eventsgeneration The typical kinematical distributions are shownin Figures 9-10
In the analysis the signal (with 120581Λ = 02TeVminus1 and1198981199051015840 = 700GeV) and the corresponding background (119882119895119881)
are taken into accountThe 119904-channel contribution to the sig-nal process appears as a resonance around the 1199051015840mass value inthe reconstructed invariant mass 119898rec
1199051015840 The reconstructed
mass distribution for the 1199051015840 signal (reconstructed from a topquark and a vector boson) is shown in Figure 11
Similar to the single top processes the top quark in thefinal state is reconstructed from a leading jet (commonly 119887jet)and a119882 boson (which can be reconstructed from its leptonicor hadronic decay) For the 119905120574 production we require
8 Advances in High Energy Physics
500 600 700 800 900 1000
Mt998400 (GeV)
01
02
03
04
05120581Λ
(TeV
minus1 )
t998400 rarr WbZ
t998400 rarr Wb120574
t998400 rarr Wbg
Figure 8The contour plot of anomalous coupling and mass of newheavy quark 1199051015840 for the dynamical parametrization explained in thetext with a significance of 3120590 atradic119904 = 13TeV and 119871 int = 100fb
minus1
50 100 150 200 250 300 350 400
Entr
ies
0
2000
4000
6000
8000
10000
12000
14000
16000
PhotonJet 1
Jet 2Jet 3
pT (GeV)
Figure 9 Transverse momentum distributions of leading jet (Jet 1)and other jets (Jet 2 and Jet 3) and photon for signal (119905120574 production)after detector simulation
systematically the large transverse momentum of photon(119901120574119879gt 100GeV) minimum jet transverse momentum (119901119895
119879gt
20GeV) and the pseudorapidity range (|120578119895120574| lt 25) inaddition to the requirements on mass reconstruction of119882-boson and top quark The large 119901120574
119879and the requirement of
single 119887-tagging allow a better separation of the signal (for 119905120574channel) from the background Other channels for 119905119892 and 119905119885productions are more challenging due to a large number ofjets which require additional discriminators such as angularandor total transverse energy variables However in orderto get rid of the backgrounds from 119882119905 and 119905119905 production
Entr
ies
50 100 150 200 250 300 350 4000
5000
10000
15000
20000
25000
PhotonJet 1
Jet 2Jet 3
pT (GeV)
Figure 10 Transverse momentum distributions of leading jet (Jet1) and other jets (Jet 2 and Jet 3) and photon for background (119882119895120574production)
500 600 700 800 900 1000
40
60
80
100
120
BackgroundSignal
Mrect998400
(GeV)
Even
ts10
GeV
Figure 11The reconstructedmass distributions for background andsignal (119905120574) with119898
1199051015840 = 700GeV and 120581Λ = 015TeVminus1
(for a similar framework the production cross sections areabout 25 pb and 340 pb resp) one can consider the channel3119897 + 119887jet + MET for a distinctive signal from the 1199051015840 rarr 119905119885An analysis of the investigation of single top production withsimilar backgrounds at the LHC can be found in [33ndash35]
42 Analysis of the Process 119901119901 rarr 119887119881 + 119883 (119881 = 119892 119885 120574) for1198871015840 Signal The signal process 119901119901 rarr 119887119881 + 119883 (119881 = 119892 119885 120574)includes the new heavy quark 1198871015840 exchange in both the 119904-channel and the 119905-channel The 119904-channel contributes to thesignal process as resonance around the 1198871015840mass value in the 119887119881invariantmass while the 119905-channel contributes to the nonres-onant behaviour For this process we consider the leptonicdecay of 119885 boson In the analyses we consider the 1198871015840 signalto be 119887jet + 120574 119887jet + 119895 and 119887jet + dilepton
Advances in High Energy Physics 9
Table 11 The cross sections (in pb) for 1198871015840 signal in different decay channel for parametrization PI with 119901119879cuts on the jets and photon and
|120578119895120574| lt 25 at the center of mass energyradic119904 = 13TeV
SignalMass (GeV)
PI119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887120574 + 119883
500 564 times 10minus2
562 times 10minus2
549 times 10minus2
395 times 10minus2
600 396 times 10minus2
396 times 10minus2
390 times 10minus2
333 times 10minus2
700 287 times 10minus2
287 times 10minus2
286 times 10minus2
259 times 10minus2
800 212 times 10minus2
213 times 10minus2
212 times 10minus2
199 times 10minus2
900 160 times 10minus2
160 times 10minus2
160 times 10minus2
153 times 10minus2
1000 122 times 10minus2
122 times 10minus2
122 times 10minus2
119 times 10minus2
119901119901 rarr 119887119892 + 119883
500 813 times 100
813 times 100
793 times 100
596 times 100
600 559 times 100
559 times 100
553 times 100
488 times 100
700 398 times 100
398 times 100
396 times 100
373 times 100
800 291 times 100
291 times 100
290 times 100
281 times 100
900 216 times 100
216 times 100
216 times 100
214 times 100
1000 164 times 100
163 times 100
163 times 100
162 times 100
119901119901 rarr 119887119885 + 119883
500 787 times 10minus1
781 times 10minus1
750 times 10minus1
479 times 10minus1
600 548 times 10minus1
548 times 10minus1
531 times 10minus1
427 times 10minus1
700 395 times 10minus1
394 times 10minus1
386 times 10minus1
339 times 10minus1
800 292 times 10minus1
291 times 10minus1
286 times 10minus1
261 times 10minus1
900 218 times 10minus1
218 times 10minus1
215 times 10minus1
202 times 10minus1
1000 166 times 10minus1
166 times 10minus1
164 times 10minus1
156 times 10minus1
We have obtained the cross sections by using the pseu-dorapidity cuts |120578
119895120574| lt 25 and transverse momentum cuts
119901119895120574
119879gt 20ndash200GeV for jets and photon in Table 11 (Tables
12 and 13) for PI (PII PIII) parametrizations respectivelyInvariantmass distribution of the 119887119881 (where119881 = 120574 119892 and119885)system is shown in Figure 12 for PI parametrization of thesignal with 120581Λ = 02TeVminus1 and 119898
1198871015840 = 700GeV at the
center of mass energy radic119904 = 13TeV It appears from sig-nal significance calculation that the optimized transversemomentum cut is 119901
119879gt 200GeV for 1198871015840 analyses
The backgrounds for the final state 119887(119887)119881 (where 119881 equiv
photon jet and 119885 boson) are given in Table 14 We apply thefollowing cuts to the final state photon and jets as |120578
119895120574| lt 25
and 119901119895120574119879gt 20ndash200GeV It can be noted that the background
cross section decreases as the119901119879cuts increaseWe assume the
efficiency for 119887-tagging to be 120576119887= 50and the rejection ratios
to be 10 for 119888 (119888) quark jets and 1 for light quark jetsIn order to reach 3120590 significance for the signal of 1198871015840
anomalous interactions the required integrated luminosityis shown in Figures 13ndash15 for parametrizations PI PII andPIII at the LHC with radic119904 = 13TeV The channel 1198871015840 rarr 119887120574
requires more integrated luminosity than the other channelsBy requiring the signal significance 119878119878 = 3 the contour plotsof 120581Λ and mass of 1198871015840 quark are presented in Figure 16 Theresults show that one can discover the 1198871015840 quark anomalouscouplings down to 01 in the 119887119892 channel for119898
1198871015840 = 500GeV
500 600 700 800 900 100010minus6
10minus5
10minus4
10minus3
10minus2
10minus1
100
d120590d
mbV
(pb
GeV
)
MbV (GeV)
pp rarr bg + X
pprarr bZ + X
pprarr b120574 + X
Figure 12 Invariant mass distribution of the 119887119881 (where 119881 = 120574 119892and 119885) system is shown in Figure 5 for PI parametrization of thesignal with 120581Λ = 02TeVminus1 and 119898
1198871015840 = 700GeV at the center of
mass energyradic119904 = 13TeV
421 Simulation for 1198871015840 Signal In the simulation we havegenerated 119887119881 (where 119881 = 120574 119892 and 119885) events for each sub-process and these events are simulated using generic detector
10 Advances in High Energy Physics
Table 12 The same as Table 11 but for parametrization PII
SignalMass (GeV)
PII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887120574 + 119883
500 518 times 10minus3
526 times 10minus3
504 times 10minus3
354 times 10minus3
600 338 times 10minus3
337 times 10minus3
336 times 10minus3
277 times 10minus3
700 232 times 10minus3
231 times 10minus3
230 times 10minus3
205 times 10minus3
800 171 times 10minus3
163 times 10minus3
164 times 10minus3
150 times 10minus3
900 117 times 10minus3
116 times 10minus3
117 times 10minus3
111 times 10minus3
1000 860 times 10minus4
858 times 10minus4
855 times 10minus4
824 times 10minus4
119901119901 rarr 119887119892 + 119883
500 740 times 10minus1
739 times 10minus1
721 times 10minus1
516 times 10minus1
600 483 times 10minus1
480 times 10minus1
481 times 10minus1
398 times 10minus1
700 322 times 10minus1
322 times 10minus1
320 times 10minus1
289 times 10minus1
800 224 times 10minus1
221 times 10minus1
221 times 10minus1
204 times 10minus1
900 15 times 10minus1
158 times 10minus1
158 times 10minus1
149 times 10minus1
1000 114 times 10minus1
114 times 10minus1
113 times 10minus1
110 times 10minus1
119901119901 rarr 119887119885 + 119883
500 689 times 10minus2
685 times 10minus2
645 times 10minus2
423 times 10minus2
600 452 times 10minus2
451 times 10minus2
434 times 10minus2
353 times 10minus2
700 312 times 10minus2
311 times 10minus2
305 times 10minus2
265 times 10minus2
800 219 times 10minus2
218 times 10minus2
215 times 10minus2
195 times 10minus2
900 156 times 10minus2
156 times 10minus2
155 times 10minus2
144 times 10minus2
1000 114 times 10minus2
113 times 10minus2
113 times 10minus2
107 times 10minus2
Table 13 The same as Table 11 but for parametrization PIII
SignalMass (GeV)
PIII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887120574 + 119883
500 131 times 10minus2
1314 times 10minus2
1275 times 10minus2
892 times 10minus2
600 859 times 10minus2
858 times 10minus2
844 times 10minus2
703 times 10minus2
700 582 times 10minus2
582 times 10minus2
577 times 10minus2
517 times 10minus2
800 407 times 10minus2
407 times 10minus2
406 times 10minus2
377 times 10minus2
900 292 times 10minus2
292 times 10minus2
291 times 10minus2
277 times 10minus2
1000 214 times 10minus2
213 times 10minus2
213 times 10minus2
206 times 10minus2
119901119901 rarr 119887119892 + 119883
500 1904 times 100
1896 times 100
1843 times 100
1286 times 100
600 1219 times 100
1213 times 100
1193 times 100
992 times 100
700 808 times 100
807 times 100
802 times 100
717 times 100
800 557 times 100
557 times 100
555 times 100
515 times 100
900 394 times 100
394 times 100
394 times 100
374 times 100
1000 285 times 100
285 times 100
285 times 100
274 times 100
119901119901 rarr 119887119885 + 119883
500 176 times 100
175 times 100
165 times 100
105 times 100
600 115 times 100
114 times 100
111 times 100
880 times 10minus1
700 783 times 10minus1
780 times 10minus1
760 times 10minus1
661 times 10minus1
800 547 times 10minus1
541 times 10minus1
531 times 10minus1
480 times 10minus1
900 392 times 10minus1
390 times 10minus1
382 times 10minus1
360 times 10minus1
1000 286 times 10minus1
282 times 10minus1
280 times 10minus1
262 times 10minus1
Advances in High Energy Physics 11
Table 14 The cross sections (in pb) for the backgrounds (119887(119887)119881 119888(119888)119881 and 119895119881 where119881 = photon jet and 119885 boson) with 119901119879cuts on the jets
and photon at the center of mass energy radic119904 = 13TeV
Background 119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887(119887)120574 + 119883 299 times 103
135 times 102
904 times 100
402 times 10minus1
119901119901 rarr 119888(119888)120574 + 119883 187 times 104
815 times 102
540 times 101
243 times 100
119901119901 rarr 119895120574 + 119883 543 times 104
327 times 103
338 times 102
285 times 101
119901119901 rarr 119887(119887)119895 + 119883 783 times 106
305 times 105
192 times 104
893 times 102
119901119901 rarr 119888(119888)119895 + 119883 122 times 107
455 times 105
289 times 104
135 times 103
119901119901 rarr 119895119895 + 119883 243 times 108
854 times 106
544 times 105
280 times 104
119901119901 rarr 119887(119887)119885 + 119883 502 times 102
135 times 102
225 times 101
156 times 100
119901119901 rarr 119888(119888)119885 + 119883 596 times 102
158 times 102
264 times 101
183 times 100
119901119901 rarr 119895119885 + 119883 800 times 103
208 times 103
408 times 102
412 times 101
500 600 700 800 900 1000
Mb998400 (GeV)
10minus1
100
101
102
103
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Figure 13 Integrated luminosity required to reach 3120590 significancefor the signal of 1198871015840 anomalous interactions for parametrization PI atthe LHC withradic119904 = 13TeV
500 600 700 800 900 1000
Mb998400 (GeV)
104
101
102
103
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Figure 14 The same as Figure 13 but for parametrization PII
500 600 700 800 900 100010minus1
100
101
102
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Mb998400 (GeV)
Figure 15 The same as Figure 13 but for parametrization PIII
parameters to include detector effects such as tracking tag-ging efficiencies and smearing effects After the simulationthe typical kinematical distributions are shown in Figures 17-18
In the analysis the signal (with 120581Λ = 03TeVminus1 and1198981198871015840 = 700GeV) and the corresponding background are
taken into account The invariant mass of the new heavyquark 1198871015840 can be reconstructed from a 119887jet and a neutral gaugeboson (where the 119885 boson can also be reconstructed fromits dilepton or hadronic decay) For the 119887120574 production werequire a large 119901120574
119879(gt100GeV) for photon and large 119901119895
119879
(gt100GeV) for jet and pseudorapidity |120578119895120574| (lt25) For the 119887120574signal channel the invariantmass distributions for signal andbackground events are shown in Figure 19The large 119901119895120574
119879and
the requirement of single 119887-tagging allow a better separationof the signal (for 119887120574 channel) from the background and thenwe find a precise limit for the anomalous coupling in thischannel For the 119887119892 and 119887119885 production we require two high119901119879jets (one 119887-jet) and a high 119901
119879jet in addition to the
reconstructed mass 119898rec119885 respectively The main character of
12 Advances in High Energy Physics
500 600 700 800 900 100001
02
03
04
05120581Λ
(TeV
minus1 )
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Mb998400 (GeV)
Figure 16The contour plot of anomalous coupling andmass of newheavy quark 1198871015840 for the dynamical parametrization explained in thetext with a significance of 3120590 atradic119904 = 13TeV and 119871 int = 100fb
minus1
50 100 150 200 250 300 350 400
Entr
ies
0
2000
4000
6000
8000
10000
PhotonJet 1
pT (GeV)
Figure 17 Transverse momentum distributions of leading jet andphoton (119887120574 production) for signal after detector simulation
the signal is the high 119901119895119879andor 119901120574
119879and single 119887-tagged jet
We calculate the signal and background events in the range|119898
rec1198871015840 (GeV) minus 700GeV| lt 50GeV and we find a similar
significance as shown in Figure 16
5 Conclusion
The new heavy quarks of up-type and down-type can be pro-duced with large numbers at the LHC if they have the anoma-lous couplings (via flavor changing neutral current) thatwell dominate over the charged current interactions The
Entr
ies
50 100 150 200 250 300 350 4000
2000
4000
6000
8000
10000
12000
PhotonJet 1
pT (GeV)
Figure 18 Transverse momentum distributions of leading jet andphoton (119895120574 production) for background at the given conditionsmentioned in the text
500 550 600 650 700 750 800 850 900 950 10000
500
1000
1500
2000
2500
3000
BackgroundSignal
Mrecb998400
(GeV)
Even
ts10
GeV
Figure 19The reconstructedmass distributions for background andsignal (119887120574) with119898
1198871015840 = 700GeV and 120581Λ = 03TeVminus1
single production of new heavy quarks can be achievedthrough the anomalous interactions at the LHC with radic119904 =13TeV The anomalous vertices could appear significantly atleading order processes due to the possibility of new heavyquarks From the results of signal significance calculationsfor 1199051015840 (1198871015840) anomalous productions the sensitivity to theanomalous couplings 120581119905
1015840
Λ (1205811198871015840
Λ) can be reached down to010 TeVminus1 (015 TeVminus1) in the lepton + 119887jet + jet +MET (119887jet +jet) channel at radic119904 = 13TeV assuming a dynamical para-metrization for the anomalous couplings and the mass of 750GeV for the new heavy quarks The observability limits onthe anomalous couplings obtained after the simulation arecomparable with the partonic level analysis in the photon and119885 boson associated channels whereas the productions 119905119892 and119887119892 are less comparable due to the fast simulation method In
Advances in High Energy Physics 13
any case the single 119887 tagging will play an important role inprobing new heavy quarks and reducing the background
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgment
This work was supported in part by Turkish Atomic EnergyAuthority (TAEA) under Project Grant no 2011TAEKCERN-A5H2P101-19
References
[1] H J He N Polonsky and S F Su ldquoExtra families Higgs spec-trum and oblique correctionsrdquo Physical Review D vol 64 no5 Article ID 053004 11 pages 2001
[2] B Holdom W S Hou T Hurth M L Mangano S Sultansoyand G Unel ldquoFour statements about the fourth generationrdquoPMC Physics A vol 3 article 4 2009
[3] A Atre M Carena T Han and J Santiago ldquoHeavy quarksabove the top at the Tevatronrdquo Physical ReviewD vol 79 ArticleID 054018 2009
[4] A Atre G Azuelos M Carena et al ldquoModel-independentsearches for new quarks at the LHCrdquo Journal of High EnergyPhysics vol 2011 no 8 article 080 2011
[5] N Chen and H J He ldquoLHC signatures of two-Higgs-doubletswith fourth familyrdquo Journal of High Energy Physics vol 2012article 062 2012
[6] M S Chanowitz ldquoElectroweak constraints on the fourth gener-ation at two loop orderrdquo Physical Review D vol 88 Article ID015012 2013
[7] S Chakdar K Ghosh S Nandi and S K Rai ldquoCollider signa-tures of mirror fermions in the framework of a left-right mirrormodelrdquo Physical Review D vol 88 Article ID 095005 2013
[8] X F Wang C Du and H J He ldquoLHC Higgs signatures fromtopflavor seesaw mechanismrdquo Physics Letters B vol 723 no 4-5 pp 314ndash323 2013
[9] S Bar-Shalom M Geller S Nandi and A Soni ldquoTwo higgsdoublets a 4th generation and a 125GeV higgs a reviewrdquoAdvances in High Energy Physics vol 2013 Article ID 67297228 pages 2013
[10] H Fritzsch and D Holtmannspotter ldquoThe production of singlet-quarks at LEP and HERArdquo Physics Letters B vol 457 no 1ndash3pp 186ndash192 1999
[11] G Aad B Abbott J Abdallah et al ldquoSearch for down-typefourth generation quarks with the ATLAS detector in eventswith one lepton and hadronically decaying119882 bosonsrdquo PhysicalReview Letters vol 109 Article ID 032001 2012
[12] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoSearchfor pair produced fourth-generation up-type quarks in ppcollisions atradic119904 = 7 TeV with a lepton in the final staterdquo PhysicsLetters B vol 718 pp 307ndash328 2012
[13] G Aad B Abbott J Abdallah et al ldquoSearch for pair and singleproduction of new heavy quarks that decay to a Z boson and athird-generation quark in pp collisions at radic119904 = 8TeV with theATLAS detectorrdquo Journal of High Energy Physics vol 2014 no11 article 104 2014
[14] G Aad T Abajyan B Abbott et al ldquoSearch for pair productionof heavy top-like quarks decaying to a high-pTW boson and ab quark in the lepton plus jets final state at radic119904 = 7TeV with theATLAS detectorrdquo Physics Letters B vol 718 no 4ndash5 pp 1284ndash1302 2013
[15] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoSearchfor heavy top-like quark pair production in the dilepton finalstate in pp collisions at radic119904 = 7TeVrdquo Physics Letters B vol 716no 1 pp 103ndash121 2012
[16] G Aad B Abbott J Abdallah et al ldquoSearch for heavy vector-like quarks coupling to light quarks in protonndashproton collisionsat radic119904 = 7 Tev with the ATLAS detectorrdquo Physics Letters B vol712 no 1-2 pp 22ndash39 2012
[17] G Aad T Abajyan B Abbott et al ldquoSearch for a heavy top-quark partner in final states with two leptons with the ATLASdetector at the LHCrdquo Journal of High Energy Physics vol 2012article 94 2012
[18] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoCom-bined search for the quarks of a sequential fourth generationrdquoPhysical Review D vol 86 no 11 Article ID 112003 20 pages2012
[19] R Ciftci ldquoAnomalous single production of the fourth gener-ation quarks at the CERN LHCrdquo Physical Review D vol 78Article ID 075018 2008
[20] I T Cakır H D Yıldız O Cakır and G Unel ldquoAnomalousresonant production of the fourth-family up-type quarks at theLHCrdquo Physical Review D vol 80 Article ID 095009 2009
[21] M Sahin S Sultansoy and S Turkoz ldquoSearching for the fourthfamily quarks through anomalous decaysrdquo Physical Review Dvol 82 no 5 Article ID 051503 2010
[22] M Bobrowski A Lenz J Riedl and J Rohrwild ldquoHow muchspace is left for a new family of fermionsrdquo Physical Review Dvol 79 no 11 Article ID 113006 15 pages 2009
[23] G Eilam B Melic and J Trampetic ldquo119862119875 violation and thefourth generationrdquo Physical Review D vol 80 no 11 Article ID116003 2009
[24] O Cobanoglu E Ozcan S Sultansoy and G Unel ldquoOPUCEMa library with error checkingmechanism for computing obliqueparametersrdquo Computer Physics Communications vol 182 no 8pp 1732ndash1743 2011
[25] T Han and J L Hewett ldquoTop-charm associated production inhigh energy 119890+119890minus collisionsrdquo Physical Review D vol 60 ArticleID 074015 1999
[26] A Belyaev N D Christensen and A Pukhov ldquoCalcHEP 34for collider physics within and beyond the standard modelrdquoComputer Physics Communications vol 184 no 7 pp 1729ndash1769 2013
[27] J Pumplin D Robert Stump J Huston H-L Lai P Nadolskyand W-K Tung ldquoNew generation of Parton distributions withuncertainties from global QCD analysisrdquo Journal of High EnergyPhysics vol 2002 article 012 2002
[28] G L Bayatian S Chatrchyan G Hmayakyan et al ldquoCMSphysics technical design report volume II physics perfor-mancerdquo Journal of Physics G Nuclear and Particle Physics vol34 no 6 p 995 2007
[29] T Sjostrand S Mrenna and P Skands ldquoPYTHIA 64 physicsand manualrdquo Journal of High Energy Physics vol 2006 no 5 p026 2006
[30] J Conway R Culbertson and R Demina Pretty Good Sim-ulation (PGS4) httpwwwphysicsucdavisedusimconwayresearchsoftwarepgspgs4-generalhtm
14 Advances in High Energy Physics
[31] EXROOTANALYSIS package for PGS4 data analysishttpmadgraphhepuiuceduDownloadsExRootAnalysis
[32] R Brun et al An object oriented data analysis framework(ROOT) httpsrootcernchdrupal
[33] F del Aguila and J A Aguilar-Saavedra ldquoMultilepton produc-tion via top flavour-changing neutral couplings at the CERNLHCrdquo Nuclear Physics B vol 576 pp 56ndash84 2000
[34] T Han M Hosch K Whisnant B-L Young and X ZhangldquoSingle top quark production via FCNC couplings at hadroncollidersrdquo Physical Review D vol 58 Article ID 073008 1998
[35] T Stelzer Z Sullivan and S Willenbrock ldquoSingle-top-quarkproduction at hadron collidersrdquoPhysical ReviewD vol 58 no 9Article ID 094021 11 pages 1998
Table 8 The same as Table 7 but for parametrization PII
SignalMass (GeV)
PII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119882+119887120574 + 119883
500 678 times 10minus3
507 times 10minus3
345 times 10minus3
264 times 10minus7
600 657 times 10minus3
542 times 10minus3
347 times 10minus3
534 times 10minus4
700 502 times 10minus3
431 times 10minus3
304 times 10minus3
873 times 10minus4
800 391 times 10minus3
376 times 10minus3
256 times 10minus3
103 times 10minus3
900 303 times 10minus3
268 times 10minus3
211 times 10minus3
101 times 10minus3
1000 240 times 10minus3
243 times 10minus3
177 times 10minus3
998 times 10minus4
119901119901 rarr 119882+119887119892 + 119883
500 347 times 10minus1
268 times 10minus1
152 times 10minus1
530 times 10minus6
600 251 times 10minus1
212 times 10minus1
135 times 10minus1
201 times 10minus2
700 187 times 10minus1
16 times 10minus1
116 times 10minus1
342 times 10minus2
800 146 times 10minus1
125 times 10minus1
939 times 10minus2
403 times 10minus2
900 112 times 10minus1
108 times 10minus1
780 times 10minus2
386 times 10minus2
1000 935 times 10minus2
837 times 10minus2
662 times 10minus2
368 times 10minus2
119901119901 rarr 119882+119887119885+119883
500 210 times 10minus2
177 times 10minus2
116 times 10minus2
264 times 10minus7
600 195 times 10minus2
175 times 10minus2
114 times 10minus2
134 times 10minus3
700 173 times 10minus2
143 times 10minus2
100 times 10minus2
29 times 10minus3
800 134 times 10minus2
119 times 10minus2
889 times 10minus3
342 times 10minus3
900 106 times 10minus2
955 times 10minus3
763 times 10minus3
337 times 10minus3
1000 809 times 10minus3
758 times 10minus3
631 times 10minus3
323 times 10minus3
Table 9 The same as Table 7 but for parametrization PIII
SignalMass (GeV)
PIII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119882+119887120574 + 119883
500 260 times 10minus1
278 times 10minus1
108 times 10minus1
159 times 10minus4
600 178 times 10minus1
161 times 10minus1
101 times 10minus1
142 times 10minus2
700 156 times 10minus1
135 times 10minus1
933 times 10minus2
272 times 10minus2
800 117 times 10minus1
106 times 10minus1
784 times 10minus2
332 times 10minus2
900 904 times 10minus2
842 times 10minus2
668 times 10minus2
325 times 10minus2
1000 760 times 10minus2
676 times 10minus2
516 times 10minus2
317 times 10minus2
119901119901 rarr 119882+119887119892 + 119883
500 839 times 100
649 times 100
386 times 100
465 times 10minus3
600 610 times 100
578 times 100
381 times 100
556 times 10minus1
700 539 times 100
464 times 100
341 times 100
970 times 10minus1
800 394 times 100
354 times 100
273 times 100
105 times 100
900 324 times 100
276 times 100
227 times 100
107 times 100
1000 233 times 100
229 times 100
184 times 100
998 times 10minus1
119901119901 rarr 119882+119887119885+119883
500 772 times 10minus1
101 times 100
217 times 10minus1
627 times 10minus4
600 624 times 10minus1
385 times 10minus1
292 times 10minus1
320 times 10minus2
700 500 times 10minus1
305 times 10minus1
286 times 10minus1
580 times 10minus2
800 378 times 10minus1
250 times 10minus1
242 times 10minus1
964 times 10minus2
900 304 times 10minus1
167 times 10minus1
206 times 10minus1
962 times 10minus2
1000 251 times 10minus1
129 times 10minus1
148 times 10minus1
961 times 10minus2
Advances in High Energy Physics 7
Table 10The cross sections (in pb) for the relevant backgrounds (119882+119887(119887)119881119882+119888(119888)119881 and119882+119895119881 where119881 = photon jet and119885 boson) with119901119879cuts on the jets at the center of mass energyradic119904 = 13TeV
Background 119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119882+119887120574 + 119883 237 times 10
minus3362 times 10
minus4617 times 10
minus5699 times 10
minus6
119901119901 rarr 119882+119888120574 + 119883 415 times 10
0459 times 10
minus1625 times 10
minus2621 times 10
minus3
119901119901 rarr 119882+119895120574 + 119883 263 times 10
1430 times 10
0733 times 10
minus1127 times 10
minus1
119901119901 rarr 119882+119887(119887)119895 + 119883 726 times 10
1302 times 10
1611 times 10
0974 times 10
minus1
119901119901 rarr 119882+119888(119888)119895 + 119883 598 times 10
2965 times 10
1179 times 10
1242 times 10
0
119901119901 rarr 119882+119895119895 + 119883 731 times 10
3778 times 10
2161 times 10
2258 times 10
1
119901119901 rarr 119882+119887119885 + 119883 626 times 10
minus4399 times 10
minus4193 times 10
minus4471 times 10
minus5
119901119901 rarr 119882+119888119885 + 119883 529 times 10
minus1340 times 10
minus1166 times 10
minus1415 times 10
minus2
119901119901 rarr 119882+119895119885 + 119883 859 times 10
0483 times 10
0249 times 10
0791 times 10
minus1
500 600 700 800 900 100010minus2
10minus1
100
101
102
103
t998400 rarr tZ
t998400 rarr t120574
t998400 rarr tg
Mt998400 (GeV)
Lin
t(fb
minus1)
Figure 5 Integrated luminosity required to reach 3120590 significancefor the signal of 1199051015840 anomalous interactions for parametrization PI atthe LHC withradic119904 = 13TeV
102
103
104
500 600 700 800 900 1000
t998400 rarr tZ
t998400 rarr t120574
t998400 rarr tg
Mt998400 (GeV)
Lin
t(fb
minus1)
Figure 6 The same as Figure 5 but for parametrization PII
500 600 700 800 900 100010minus2
10minus1
100
101
102
103
t998400 rarr tZ
t998400 rarr t120574
t998400 rarr tg
Mt998400 (GeV)
Lin
t(fb
minus1)
Figure 7 The same as Figure 5 but for parametrization PIII
detector parametersThis fast simulation includes the impor-tant detector effects such as tracking smearing effects of thecalorimeters resolution and tag efficiencies The EXROOT-ANALYSIS package [31] is used for the simulated events andthe output is analyzed and histogrammed with the ROOT[32] macros We consider jets (up to five) leptons (electronsor muons) photons and missing transverse momentumwithin the simulated events for the 119905120574 119905119895 and 119905119885 eventsgeneration The typical kinematical distributions are shownin Figures 9-10
In the analysis the signal (with 120581Λ = 02TeVminus1 and1198981199051015840 = 700GeV) and the corresponding background (119882119895119881)
are taken into accountThe 119904-channel contribution to the sig-nal process appears as a resonance around the 1199051015840mass value inthe reconstructed invariant mass 119898rec
1199051015840 The reconstructed
mass distribution for the 1199051015840 signal (reconstructed from a topquark and a vector boson) is shown in Figure 11
Similar to the single top processes the top quark in thefinal state is reconstructed from a leading jet (commonly 119887jet)and a119882 boson (which can be reconstructed from its leptonicor hadronic decay) For the 119905120574 production we require
8 Advances in High Energy Physics
500 600 700 800 900 1000
Mt998400 (GeV)
01
02
03
04
05120581Λ
(TeV
minus1 )
t998400 rarr WbZ
t998400 rarr Wb120574
t998400 rarr Wbg
Figure 8The contour plot of anomalous coupling and mass of newheavy quark 1199051015840 for the dynamical parametrization explained in thetext with a significance of 3120590 atradic119904 = 13TeV and 119871 int = 100fb
minus1
50 100 150 200 250 300 350 400
Entr
ies
0
2000
4000
6000
8000
10000
12000
14000
16000
PhotonJet 1
Jet 2Jet 3
pT (GeV)
Figure 9 Transverse momentum distributions of leading jet (Jet 1)and other jets (Jet 2 and Jet 3) and photon for signal (119905120574 production)after detector simulation
systematically the large transverse momentum of photon(119901120574119879gt 100GeV) minimum jet transverse momentum (119901119895
119879gt
20GeV) and the pseudorapidity range (|120578119895120574| lt 25) inaddition to the requirements on mass reconstruction of119882-boson and top quark The large 119901120574
119879and the requirement of
single 119887-tagging allow a better separation of the signal (for 119905120574channel) from the background Other channels for 119905119892 and 119905119885productions are more challenging due to a large number ofjets which require additional discriminators such as angularandor total transverse energy variables However in orderto get rid of the backgrounds from 119882119905 and 119905119905 production
Entr
ies
50 100 150 200 250 300 350 4000
5000
10000
15000
20000
25000
PhotonJet 1
Jet 2Jet 3
pT (GeV)
Figure 10 Transverse momentum distributions of leading jet (Jet1) and other jets (Jet 2 and Jet 3) and photon for background (119882119895120574production)
500 600 700 800 900 1000
40
60
80
100
120
BackgroundSignal
Mrect998400
(GeV)
Even
ts10
GeV
Figure 11The reconstructedmass distributions for background andsignal (119905120574) with119898
1199051015840 = 700GeV and 120581Λ = 015TeVminus1
(for a similar framework the production cross sections areabout 25 pb and 340 pb resp) one can consider the channel3119897 + 119887jet + MET for a distinctive signal from the 1199051015840 rarr 119905119885An analysis of the investigation of single top production withsimilar backgrounds at the LHC can be found in [33ndash35]
42 Analysis of the Process 119901119901 rarr 119887119881 + 119883 (119881 = 119892 119885 120574) for1198871015840 Signal The signal process 119901119901 rarr 119887119881 + 119883 (119881 = 119892 119885 120574)includes the new heavy quark 1198871015840 exchange in both the 119904-channel and the 119905-channel The 119904-channel contributes to thesignal process as resonance around the 1198871015840mass value in the 119887119881invariantmass while the 119905-channel contributes to the nonres-onant behaviour For this process we consider the leptonicdecay of 119885 boson In the analyses we consider the 1198871015840 signalto be 119887jet + 120574 119887jet + 119895 and 119887jet + dilepton
Advances in High Energy Physics 9
Table 11 The cross sections (in pb) for 1198871015840 signal in different decay channel for parametrization PI with 119901119879cuts on the jets and photon and
|120578119895120574| lt 25 at the center of mass energyradic119904 = 13TeV
SignalMass (GeV)
PI119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887120574 + 119883
500 564 times 10minus2
562 times 10minus2
549 times 10minus2
395 times 10minus2
600 396 times 10minus2
396 times 10minus2
390 times 10minus2
333 times 10minus2
700 287 times 10minus2
287 times 10minus2
286 times 10minus2
259 times 10minus2
800 212 times 10minus2
213 times 10minus2
212 times 10minus2
199 times 10minus2
900 160 times 10minus2
160 times 10minus2
160 times 10minus2
153 times 10minus2
1000 122 times 10minus2
122 times 10minus2
122 times 10minus2
119 times 10minus2
119901119901 rarr 119887119892 + 119883
500 813 times 100
813 times 100
793 times 100
596 times 100
600 559 times 100
559 times 100
553 times 100
488 times 100
700 398 times 100
398 times 100
396 times 100
373 times 100
800 291 times 100
291 times 100
290 times 100
281 times 100
900 216 times 100
216 times 100
216 times 100
214 times 100
1000 164 times 100
163 times 100
163 times 100
162 times 100
119901119901 rarr 119887119885 + 119883
500 787 times 10minus1
781 times 10minus1
750 times 10minus1
479 times 10minus1
600 548 times 10minus1
548 times 10minus1
531 times 10minus1
427 times 10minus1
700 395 times 10minus1
394 times 10minus1
386 times 10minus1
339 times 10minus1
800 292 times 10minus1
291 times 10minus1
286 times 10minus1
261 times 10minus1
900 218 times 10minus1
218 times 10minus1
215 times 10minus1
202 times 10minus1
1000 166 times 10minus1
166 times 10minus1
164 times 10minus1
156 times 10minus1
We have obtained the cross sections by using the pseu-dorapidity cuts |120578
119895120574| lt 25 and transverse momentum cuts
119901119895120574
119879gt 20ndash200GeV for jets and photon in Table 11 (Tables
12 and 13) for PI (PII PIII) parametrizations respectivelyInvariantmass distribution of the 119887119881 (where119881 = 120574 119892 and119885)system is shown in Figure 12 for PI parametrization of thesignal with 120581Λ = 02TeVminus1 and 119898
1198871015840 = 700GeV at the
center of mass energy radic119904 = 13TeV It appears from sig-nal significance calculation that the optimized transversemomentum cut is 119901
119879gt 200GeV for 1198871015840 analyses
The backgrounds for the final state 119887(119887)119881 (where 119881 equiv
photon jet and 119885 boson) are given in Table 14 We apply thefollowing cuts to the final state photon and jets as |120578
119895120574| lt 25
and 119901119895120574119879gt 20ndash200GeV It can be noted that the background
cross section decreases as the119901119879cuts increaseWe assume the
efficiency for 119887-tagging to be 120576119887= 50and the rejection ratios
to be 10 for 119888 (119888) quark jets and 1 for light quark jetsIn order to reach 3120590 significance for the signal of 1198871015840
anomalous interactions the required integrated luminosityis shown in Figures 13ndash15 for parametrizations PI PII andPIII at the LHC with radic119904 = 13TeV The channel 1198871015840 rarr 119887120574
requires more integrated luminosity than the other channelsBy requiring the signal significance 119878119878 = 3 the contour plotsof 120581Λ and mass of 1198871015840 quark are presented in Figure 16 Theresults show that one can discover the 1198871015840 quark anomalouscouplings down to 01 in the 119887119892 channel for119898
1198871015840 = 500GeV
500 600 700 800 900 100010minus6
10minus5
10minus4
10minus3
10minus2
10minus1
100
d120590d
mbV
(pb
GeV
)
MbV (GeV)
pp rarr bg + X
pprarr bZ + X
pprarr b120574 + X
Figure 12 Invariant mass distribution of the 119887119881 (where 119881 = 120574 119892and 119885) system is shown in Figure 5 for PI parametrization of thesignal with 120581Λ = 02TeVminus1 and 119898
1198871015840 = 700GeV at the center of
mass energyradic119904 = 13TeV
421 Simulation for 1198871015840 Signal In the simulation we havegenerated 119887119881 (where 119881 = 120574 119892 and 119885) events for each sub-process and these events are simulated using generic detector
10 Advances in High Energy Physics
Table 12 The same as Table 11 but for parametrization PII
SignalMass (GeV)
PII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887120574 + 119883
500 518 times 10minus3
526 times 10minus3
504 times 10minus3
354 times 10minus3
600 338 times 10minus3
337 times 10minus3
336 times 10minus3
277 times 10minus3
700 232 times 10minus3
231 times 10minus3
230 times 10minus3
205 times 10minus3
800 171 times 10minus3
163 times 10minus3
164 times 10minus3
150 times 10minus3
900 117 times 10minus3
116 times 10minus3
117 times 10minus3
111 times 10minus3
1000 860 times 10minus4
858 times 10minus4
855 times 10minus4
824 times 10minus4
119901119901 rarr 119887119892 + 119883
500 740 times 10minus1
739 times 10minus1
721 times 10minus1
516 times 10minus1
600 483 times 10minus1
480 times 10minus1
481 times 10minus1
398 times 10minus1
700 322 times 10minus1
322 times 10minus1
320 times 10minus1
289 times 10minus1
800 224 times 10minus1
221 times 10minus1
221 times 10minus1
204 times 10minus1
900 15 times 10minus1
158 times 10minus1
158 times 10minus1
149 times 10minus1
1000 114 times 10minus1
114 times 10minus1
113 times 10minus1
110 times 10minus1
119901119901 rarr 119887119885 + 119883
500 689 times 10minus2
685 times 10minus2
645 times 10minus2
423 times 10minus2
600 452 times 10minus2
451 times 10minus2
434 times 10minus2
353 times 10minus2
700 312 times 10minus2
311 times 10minus2
305 times 10minus2
265 times 10minus2
800 219 times 10minus2
218 times 10minus2
215 times 10minus2
195 times 10minus2
900 156 times 10minus2
156 times 10minus2
155 times 10minus2
144 times 10minus2
1000 114 times 10minus2
113 times 10minus2
113 times 10minus2
107 times 10minus2
Table 13 The same as Table 11 but for parametrization PIII
SignalMass (GeV)
PIII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887120574 + 119883
500 131 times 10minus2
1314 times 10minus2
1275 times 10minus2
892 times 10minus2
600 859 times 10minus2
858 times 10minus2
844 times 10minus2
703 times 10minus2
700 582 times 10minus2
582 times 10minus2
577 times 10minus2
517 times 10minus2
800 407 times 10minus2
407 times 10minus2
406 times 10minus2
377 times 10minus2
900 292 times 10minus2
292 times 10minus2
291 times 10minus2
277 times 10minus2
1000 214 times 10minus2
213 times 10minus2
213 times 10minus2
206 times 10minus2
119901119901 rarr 119887119892 + 119883
500 1904 times 100
1896 times 100
1843 times 100
1286 times 100
600 1219 times 100
1213 times 100
1193 times 100
992 times 100
700 808 times 100
807 times 100
802 times 100
717 times 100
800 557 times 100
557 times 100
555 times 100
515 times 100
900 394 times 100
394 times 100
394 times 100
374 times 100
1000 285 times 100
285 times 100
285 times 100
274 times 100
119901119901 rarr 119887119885 + 119883
500 176 times 100
175 times 100
165 times 100
105 times 100
600 115 times 100
114 times 100
111 times 100
880 times 10minus1
700 783 times 10minus1
780 times 10minus1
760 times 10minus1
661 times 10minus1
800 547 times 10minus1
541 times 10minus1
531 times 10minus1
480 times 10minus1
900 392 times 10minus1
390 times 10minus1
382 times 10minus1
360 times 10minus1
1000 286 times 10minus1
282 times 10minus1
280 times 10minus1
262 times 10minus1
Advances in High Energy Physics 11
Table 14 The cross sections (in pb) for the backgrounds (119887(119887)119881 119888(119888)119881 and 119895119881 where119881 = photon jet and 119885 boson) with 119901119879cuts on the jets
and photon at the center of mass energy radic119904 = 13TeV
Background 119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887(119887)120574 + 119883 299 times 103
135 times 102
904 times 100
402 times 10minus1
119901119901 rarr 119888(119888)120574 + 119883 187 times 104
815 times 102
540 times 101
243 times 100
119901119901 rarr 119895120574 + 119883 543 times 104
327 times 103
338 times 102
285 times 101
119901119901 rarr 119887(119887)119895 + 119883 783 times 106
305 times 105
192 times 104
893 times 102
119901119901 rarr 119888(119888)119895 + 119883 122 times 107
455 times 105
289 times 104
135 times 103
119901119901 rarr 119895119895 + 119883 243 times 108
854 times 106
544 times 105
280 times 104
119901119901 rarr 119887(119887)119885 + 119883 502 times 102
135 times 102
225 times 101
156 times 100
119901119901 rarr 119888(119888)119885 + 119883 596 times 102
158 times 102
264 times 101
183 times 100
119901119901 rarr 119895119885 + 119883 800 times 103
208 times 103
408 times 102
412 times 101
500 600 700 800 900 1000
Mb998400 (GeV)
10minus1
100
101
102
103
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Figure 13 Integrated luminosity required to reach 3120590 significancefor the signal of 1198871015840 anomalous interactions for parametrization PI atthe LHC withradic119904 = 13TeV
500 600 700 800 900 1000
Mb998400 (GeV)
104
101
102
103
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Figure 14 The same as Figure 13 but for parametrization PII
500 600 700 800 900 100010minus1
100
101
102
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Mb998400 (GeV)
Figure 15 The same as Figure 13 but for parametrization PIII
parameters to include detector effects such as tracking tag-ging efficiencies and smearing effects After the simulationthe typical kinematical distributions are shown in Figures 17-18
In the analysis the signal (with 120581Λ = 03TeVminus1 and1198981198871015840 = 700GeV) and the corresponding background are
taken into account The invariant mass of the new heavyquark 1198871015840 can be reconstructed from a 119887jet and a neutral gaugeboson (where the 119885 boson can also be reconstructed fromits dilepton or hadronic decay) For the 119887120574 production werequire a large 119901120574
119879(gt100GeV) for photon and large 119901119895
119879
(gt100GeV) for jet and pseudorapidity |120578119895120574| (lt25) For the 119887120574signal channel the invariantmass distributions for signal andbackground events are shown in Figure 19The large 119901119895120574
119879and
the requirement of single 119887-tagging allow a better separationof the signal (for 119887120574 channel) from the background and thenwe find a precise limit for the anomalous coupling in thischannel For the 119887119892 and 119887119885 production we require two high119901119879jets (one 119887-jet) and a high 119901
119879jet in addition to the
reconstructed mass 119898rec119885 respectively The main character of
12 Advances in High Energy Physics
500 600 700 800 900 100001
02
03
04
05120581Λ
(TeV
minus1 )
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Mb998400 (GeV)
Figure 16The contour plot of anomalous coupling andmass of newheavy quark 1198871015840 for the dynamical parametrization explained in thetext with a significance of 3120590 atradic119904 = 13TeV and 119871 int = 100fb
minus1
50 100 150 200 250 300 350 400
Entr
ies
0
2000
4000
6000
8000
10000
PhotonJet 1
pT (GeV)
Figure 17 Transverse momentum distributions of leading jet andphoton (119887120574 production) for signal after detector simulation
the signal is the high 119901119895119879andor 119901120574
119879and single 119887-tagged jet
We calculate the signal and background events in the range|119898
rec1198871015840 (GeV) minus 700GeV| lt 50GeV and we find a similar
significance as shown in Figure 16
5 Conclusion
The new heavy quarks of up-type and down-type can be pro-duced with large numbers at the LHC if they have the anoma-lous couplings (via flavor changing neutral current) thatwell dominate over the charged current interactions The
Entr
ies
50 100 150 200 250 300 350 4000
2000
4000
6000
8000
10000
12000
PhotonJet 1
pT (GeV)
Figure 18 Transverse momentum distributions of leading jet andphoton (119895120574 production) for background at the given conditionsmentioned in the text
500 550 600 650 700 750 800 850 900 950 10000
500
1000
1500
2000
2500
3000
BackgroundSignal
Mrecb998400
(GeV)
Even
ts10
GeV
Figure 19The reconstructedmass distributions for background andsignal (119887120574) with119898
1198871015840 = 700GeV and 120581Λ = 03TeVminus1
single production of new heavy quarks can be achievedthrough the anomalous interactions at the LHC with radic119904 =13TeV The anomalous vertices could appear significantly atleading order processes due to the possibility of new heavyquarks From the results of signal significance calculationsfor 1199051015840 (1198871015840) anomalous productions the sensitivity to theanomalous couplings 120581119905
1015840
Λ (1205811198871015840
Λ) can be reached down to010 TeVminus1 (015 TeVminus1) in the lepton + 119887jet + jet +MET (119887jet +jet) channel at radic119904 = 13TeV assuming a dynamical para-metrization for the anomalous couplings and the mass of 750GeV for the new heavy quarks The observability limits onthe anomalous couplings obtained after the simulation arecomparable with the partonic level analysis in the photon and119885 boson associated channels whereas the productions 119905119892 and119887119892 are less comparable due to the fast simulation method In
Advances in High Energy Physics 13
any case the single 119887 tagging will play an important role inprobing new heavy quarks and reducing the background
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgment
This work was supported in part by Turkish Atomic EnergyAuthority (TAEA) under Project Grant no 2011TAEKCERN-A5H2P101-19
References
[1] H J He N Polonsky and S F Su ldquoExtra families Higgs spec-trum and oblique correctionsrdquo Physical Review D vol 64 no5 Article ID 053004 11 pages 2001
[2] B Holdom W S Hou T Hurth M L Mangano S Sultansoyand G Unel ldquoFour statements about the fourth generationrdquoPMC Physics A vol 3 article 4 2009
[3] A Atre M Carena T Han and J Santiago ldquoHeavy quarksabove the top at the Tevatronrdquo Physical ReviewD vol 79 ArticleID 054018 2009
[4] A Atre G Azuelos M Carena et al ldquoModel-independentsearches for new quarks at the LHCrdquo Journal of High EnergyPhysics vol 2011 no 8 article 080 2011
[5] N Chen and H J He ldquoLHC signatures of two-Higgs-doubletswith fourth familyrdquo Journal of High Energy Physics vol 2012article 062 2012
[6] M S Chanowitz ldquoElectroweak constraints on the fourth gener-ation at two loop orderrdquo Physical Review D vol 88 Article ID015012 2013
[7] S Chakdar K Ghosh S Nandi and S K Rai ldquoCollider signa-tures of mirror fermions in the framework of a left-right mirrormodelrdquo Physical Review D vol 88 Article ID 095005 2013
[8] X F Wang C Du and H J He ldquoLHC Higgs signatures fromtopflavor seesaw mechanismrdquo Physics Letters B vol 723 no 4-5 pp 314ndash323 2013
[9] S Bar-Shalom M Geller S Nandi and A Soni ldquoTwo higgsdoublets a 4th generation and a 125GeV higgs a reviewrdquoAdvances in High Energy Physics vol 2013 Article ID 67297228 pages 2013
[10] H Fritzsch and D Holtmannspotter ldquoThe production of singlet-quarks at LEP and HERArdquo Physics Letters B vol 457 no 1ndash3pp 186ndash192 1999
[11] G Aad B Abbott J Abdallah et al ldquoSearch for down-typefourth generation quarks with the ATLAS detector in eventswith one lepton and hadronically decaying119882 bosonsrdquo PhysicalReview Letters vol 109 Article ID 032001 2012
[12] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoSearchfor pair produced fourth-generation up-type quarks in ppcollisions atradic119904 = 7 TeV with a lepton in the final staterdquo PhysicsLetters B vol 718 pp 307ndash328 2012
[13] G Aad B Abbott J Abdallah et al ldquoSearch for pair and singleproduction of new heavy quarks that decay to a Z boson and athird-generation quark in pp collisions at radic119904 = 8TeV with theATLAS detectorrdquo Journal of High Energy Physics vol 2014 no11 article 104 2014
[14] G Aad T Abajyan B Abbott et al ldquoSearch for pair productionof heavy top-like quarks decaying to a high-pTW boson and ab quark in the lepton plus jets final state at radic119904 = 7TeV with theATLAS detectorrdquo Physics Letters B vol 718 no 4ndash5 pp 1284ndash1302 2013
[15] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoSearchfor heavy top-like quark pair production in the dilepton finalstate in pp collisions at radic119904 = 7TeVrdquo Physics Letters B vol 716no 1 pp 103ndash121 2012
[16] G Aad B Abbott J Abdallah et al ldquoSearch for heavy vector-like quarks coupling to light quarks in protonndashproton collisionsat radic119904 = 7 Tev with the ATLAS detectorrdquo Physics Letters B vol712 no 1-2 pp 22ndash39 2012
[17] G Aad T Abajyan B Abbott et al ldquoSearch for a heavy top-quark partner in final states with two leptons with the ATLASdetector at the LHCrdquo Journal of High Energy Physics vol 2012article 94 2012
[18] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoCom-bined search for the quarks of a sequential fourth generationrdquoPhysical Review D vol 86 no 11 Article ID 112003 20 pages2012
[19] R Ciftci ldquoAnomalous single production of the fourth gener-ation quarks at the CERN LHCrdquo Physical Review D vol 78Article ID 075018 2008
[20] I T Cakır H D Yıldız O Cakır and G Unel ldquoAnomalousresonant production of the fourth-family up-type quarks at theLHCrdquo Physical Review D vol 80 Article ID 095009 2009
[21] M Sahin S Sultansoy and S Turkoz ldquoSearching for the fourthfamily quarks through anomalous decaysrdquo Physical Review Dvol 82 no 5 Article ID 051503 2010
[22] M Bobrowski A Lenz J Riedl and J Rohrwild ldquoHow muchspace is left for a new family of fermionsrdquo Physical Review Dvol 79 no 11 Article ID 113006 15 pages 2009
[23] G Eilam B Melic and J Trampetic ldquo119862119875 violation and thefourth generationrdquo Physical Review D vol 80 no 11 Article ID116003 2009
[24] O Cobanoglu E Ozcan S Sultansoy and G Unel ldquoOPUCEMa library with error checkingmechanism for computing obliqueparametersrdquo Computer Physics Communications vol 182 no 8pp 1732ndash1743 2011
[25] T Han and J L Hewett ldquoTop-charm associated production inhigh energy 119890+119890minus collisionsrdquo Physical Review D vol 60 ArticleID 074015 1999
[26] A Belyaev N D Christensen and A Pukhov ldquoCalcHEP 34for collider physics within and beyond the standard modelrdquoComputer Physics Communications vol 184 no 7 pp 1729ndash1769 2013
[27] J Pumplin D Robert Stump J Huston H-L Lai P Nadolskyand W-K Tung ldquoNew generation of Parton distributions withuncertainties from global QCD analysisrdquo Journal of High EnergyPhysics vol 2002 article 012 2002
[28] G L Bayatian S Chatrchyan G Hmayakyan et al ldquoCMSphysics technical design report volume II physics perfor-mancerdquo Journal of Physics G Nuclear and Particle Physics vol34 no 6 p 995 2007
[29] T Sjostrand S Mrenna and P Skands ldquoPYTHIA 64 physicsand manualrdquo Journal of High Energy Physics vol 2006 no 5 p026 2006
[30] J Conway R Culbertson and R Demina Pretty Good Sim-ulation (PGS4) httpwwwphysicsucdavisedusimconwayresearchsoftwarepgspgs4-generalhtm
14 Advances in High Energy Physics
[31] EXROOTANALYSIS package for PGS4 data analysishttpmadgraphhepuiuceduDownloadsExRootAnalysis
[32] R Brun et al An object oriented data analysis framework(ROOT) httpsrootcernchdrupal
[33] F del Aguila and J A Aguilar-Saavedra ldquoMultilepton produc-tion via top flavour-changing neutral couplings at the CERNLHCrdquo Nuclear Physics B vol 576 pp 56ndash84 2000
[34] T Han M Hosch K Whisnant B-L Young and X ZhangldquoSingle top quark production via FCNC couplings at hadroncollidersrdquo Physical Review D vol 58 Article ID 073008 1998
[35] T Stelzer Z Sullivan and S Willenbrock ldquoSingle-top-quarkproduction at hadron collidersrdquoPhysical ReviewD vol 58 no 9Article ID 094021 11 pages 1998
Table 10The cross sections (in pb) for the relevant backgrounds (119882+119887(119887)119881119882+119888(119888)119881 and119882+119895119881 where119881 = photon jet and119885 boson) with119901119879cuts on the jets at the center of mass energyradic119904 = 13TeV
Background 119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119882+119887120574 + 119883 237 times 10
minus3362 times 10
minus4617 times 10
minus5699 times 10
minus6
119901119901 rarr 119882+119888120574 + 119883 415 times 10
0459 times 10
minus1625 times 10
minus2621 times 10
minus3
119901119901 rarr 119882+119895120574 + 119883 263 times 10
1430 times 10
0733 times 10
minus1127 times 10
minus1
119901119901 rarr 119882+119887(119887)119895 + 119883 726 times 10
1302 times 10
1611 times 10
0974 times 10
minus1
119901119901 rarr 119882+119888(119888)119895 + 119883 598 times 10
2965 times 10
1179 times 10
1242 times 10
0
119901119901 rarr 119882+119895119895 + 119883 731 times 10
3778 times 10
2161 times 10
2258 times 10
1
119901119901 rarr 119882+119887119885 + 119883 626 times 10
minus4399 times 10
minus4193 times 10
minus4471 times 10
minus5
119901119901 rarr 119882+119888119885 + 119883 529 times 10
minus1340 times 10
minus1166 times 10
minus1415 times 10
minus2
119901119901 rarr 119882+119895119885 + 119883 859 times 10
0483 times 10
0249 times 10
0791 times 10
minus1
500 600 700 800 900 100010minus2
10minus1
100
101
102
103
t998400 rarr tZ
t998400 rarr t120574
t998400 rarr tg
Mt998400 (GeV)
Lin
t(fb
minus1)
Figure 5 Integrated luminosity required to reach 3120590 significancefor the signal of 1199051015840 anomalous interactions for parametrization PI atthe LHC withradic119904 = 13TeV
102
103
104
500 600 700 800 900 1000
t998400 rarr tZ
t998400 rarr t120574
t998400 rarr tg
Mt998400 (GeV)
Lin
t(fb
minus1)
Figure 6 The same as Figure 5 but for parametrization PII
500 600 700 800 900 100010minus2
10minus1
100
101
102
103
t998400 rarr tZ
t998400 rarr t120574
t998400 rarr tg
Mt998400 (GeV)
Lin
t(fb
minus1)
Figure 7 The same as Figure 5 but for parametrization PIII
detector parametersThis fast simulation includes the impor-tant detector effects such as tracking smearing effects of thecalorimeters resolution and tag efficiencies The EXROOT-ANALYSIS package [31] is used for the simulated events andthe output is analyzed and histogrammed with the ROOT[32] macros We consider jets (up to five) leptons (electronsor muons) photons and missing transverse momentumwithin the simulated events for the 119905120574 119905119895 and 119905119885 eventsgeneration The typical kinematical distributions are shownin Figures 9-10
In the analysis the signal (with 120581Λ = 02TeVminus1 and1198981199051015840 = 700GeV) and the corresponding background (119882119895119881)
are taken into accountThe 119904-channel contribution to the sig-nal process appears as a resonance around the 1199051015840mass value inthe reconstructed invariant mass 119898rec
1199051015840 The reconstructed
mass distribution for the 1199051015840 signal (reconstructed from a topquark and a vector boson) is shown in Figure 11
Similar to the single top processes the top quark in thefinal state is reconstructed from a leading jet (commonly 119887jet)and a119882 boson (which can be reconstructed from its leptonicor hadronic decay) For the 119905120574 production we require
8 Advances in High Energy Physics
500 600 700 800 900 1000
Mt998400 (GeV)
01
02
03
04
05120581Λ
(TeV
minus1 )
t998400 rarr WbZ
t998400 rarr Wb120574
t998400 rarr Wbg
Figure 8The contour plot of anomalous coupling and mass of newheavy quark 1199051015840 for the dynamical parametrization explained in thetext with a significance of 3120590 atradic119904 = 13TeV and 119871 int = 100fb
minus1
50 100 150 200 250 300 350 400
Entr
ies
0
2000
4000
6000
8000
10000
12000
14000
16000
PhotonJet 1
Jet 2Jet 3
pT (GeV)
Figure 9 Transverse momentum distributions of leading jet (Jet 1)and other jets (Jet 2 and Jet 3) and photon for signal (119905120574 production)after detector simulation
systematically the large transverse momentum of photon(119901120574119879gt 100GeV) minimum jet transverse momentum (119901119895
119879gt
20GeV) and the pseudorapidity range (|120578119895120574| lt 25) inaddition to the requirements on mass reconstruction of119882-boson and top quark The large 119901120574
119879and the requirement of
single 119887-tagging allow a better separation of the signal (for 119905120574channel) from the background Other channels for 119905119892 and 119905119885productions are more challenging due to a large number ofjets which require additional discriminators such as angularandor total transverse energy variables However in orderto get rid of the backgrounds from 119882119905 and 119905119905 production
Entr
ies
50 100 150 200 250 300 350 4000
5000
10000
15000
20000
25000
PhotonJet 1
Jet 2Jet 3
pT (GeV)
Figure 10 Transverse momentum distributions of leading jet (Jet1) and other jets (Jet 2 and Jet 3) and photon for background (119882119895120574production)
500 600 700 800 900 1000
40
60
80
100
120
BackgroundSignal
Mrect998400
(GeV)
Even
ts10
GeV
Figure 11The reconstructedmass distributions for background andsignal (119905120574) with119898
1199051015840 = 700GeV and 120581Λ = 015TeVminus1
(for a similar framework the production cross sections areabout 25 pb and 340 pb resp) one can consider the channel3119897 + 119887jet + MET for a distinctive signal from the 1199051015840 rarr 119905119885An analysis of the investigation of single top production withsimilar backgrounds at the LHC can be found in [33ndash35]
42 Analysis of the Process 119901119901 rarr 119887119881 + 119883 (119881 = 119892 119885 120574) for1198871015840 Signal The signal process 119901119901 rarr 119887119881 + 119883 (119881 = 119892 119885 120574)includes the new heavy quark 1198871015840 exchange in both the 119904-channel and the 119905-channel The 119904-channel contributes to thesignal process as resonance around the 1198871015840mass value in the 119887119881invariantmass while the 119905-channel contributes to the nonres-onant behaviour For this process we consider the leptonicdecay of 119885 boson In the analyses we consider the 1198871015840 signalto be 119887jet + 120574 119887jet + 119895 and 119887jet + dilepton
Advances in High Energy Physics 9
Table 11 The cross sections (in pb) for 1198871015840 signal in different decay channel for parametrization PI with 119901119879cuts on the jets and photon and
|120578119895120574| lt 25 at the center of mass energyradic119904 = 13TeV
SignalMass (GeV)
PI119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887120574 + 119883
500 564 times 10minus2
562 times 10minus2
549 times 10minus2
395 times 10minus2
600 396 times 10minus2
396 times 10minus2
390 times 10minus2
333 times 10minus2
700 287 times 10minus2
287 times 10minus2
286 times 10minus2
259 times 10minus2
800 212 times 10minus2
213 times 10minus2
212 times 10minus2
199 times 10minus2
900 160 times 10minus2
160 times 10minus2
160 times 10minus2
153 times 10minus2
1000 122 times 10minus2
122 times 10minus2
122 times 10minus2
119 times 10minus2
119901119901 rarr 119887119892 + 119883
500 813 times 100
813 times 100
793 times 100
596 times 100
600 559 times 100
559 times 100
553 times 100
488 times 100
700 398 times 100
398 times 100
396 times 100
373 times 100
800 291 times 100
291 times 100
290 times 100
281 times 100
900 216 times 100
216 times 100
216 times 100
214 times 100
1000 164 times 100
163 times 100
163 times 100
162 times 100
119901119901 rarr 119887119885 + 119883
500 787 times 10minus1
781 times 10minus1
750 times 10minus1
479 times 10minus1
600 548 times 10minus1
548 times 10minus1
531 times 10minus1
427 times 10minus1
700 395 times 10minus1
394 times 10minus1
386 times 10minus1
339 times 10minus1
800 292 times 10minus1
291 times 10minus1
286 times 10minus1
261 times 10minus1
900 218 times 10minus1
218 times 10minus1
215 times 10minus1
202 times 10minus1
1000 166 times 10minus1
166 times 10minus1
164 times 10minus1
156 times 10minus1
We have obtained the cross sections by using the pseu-dorapidity cuts |120578
119895120574| lt 25 and transverse momentum cuts
119901119895120574
119879gt 20ndash200GeV for jets and photon in Table 11 (Tables
12 and 13) for PI (PII PIII) parametrizations respectivelyInvariantmass distribution of the 119887119881 (where119881 = 120574 119892 and119885)system is shown in Figure 12 for PI parametrization of thesignal with 120581Λ = 02TeVminus1 and 119898
1198871015840 = 700GeV at the
center of mass energy radic119904 = 13TeV It appears from sig-nal significance calculation that the optimized transversemomentum cut is 119901
119879gt 200GeV for 1198871015840 analyses
The backgrounds for the final state 119887(119887)119881 (where 119881 equiv
photon jet and 119885 boson) are given in Table 14 We apply thefollowing cuts to the final state photon and jets as |120578
119895120574| lt 25
and 119901119895120574119879gt 20ndash200GeV It can be noted that the background
cross section decreases as the119901119879cuts increaseWe assume the
efficiency for 119887-tagging to be 120576119887= 50and the rejection ratios
to be 10 for 119888 (119888) quark jets and 1 for light quark jetsIn order to reach 3120590 significance for the signal of 1198871015840
anomalous interactions the required integrated luminosityis shown in Figures 13ndash15 for parametrizations PI PII andPIII at the LHC with radic119904 = 13TeV The channel 1198871015840 rarr 119887120574
requires more integrated luminosity than the other channelsBy requiring the signal significance 119878119878 = 3 the contour plotsof 120581Λ and mass of 1198871015840 quark are presented in Figure 16 Theresults show that one can discover the 1198871015840 quark anomalouscouplings down to 01 in the 119887119892 channel for119898
1198871015840 = 500GeV
500 600 700 800 900 100010minus6
10minus5
10minus4
10minus3
10minus2
10minus1
100
d120590d
mbV
(pb
GeV
)
MbV (GeV)
pp rarr bg + X
pprarr bZ + X
pprarr b120574 + X
Figure 12 Invariant mass distribution of the 119887119881 (where 119881 = 120574 119892and 119885) system is shown in Figure 5 for PI parametrization of thesignal with 120581Λ = 02TeVminus1 and 119898
1198871015840 = 700GeV at the center of
mass energyradic119904 = 13TeV
421 Simulation for 1198871015840 Signal In the simulation we havegenerated 119887119881 (where 119881 = 120574 119892 and 119885) events for each sub-process and these events are simulated using generic detector
10 Advances in High Energy Physics
Table 12 The same as Table 11 but for parametrization PII
SignalMass (GeV)
PII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887120574 + 119883
500 518 times 10minus3
526 times 10minus3
504 times 10minus3
354 times 10minus3
600 338 times 10minus3
337 times 10minus3
336 times 10minus3
277 times 10minus3
700 232 times 10minus3
231 times 10minus3
230 times 10minus3
205 times 10minus3
800 171 times 10minus3
163 times 10minus3
164 times 10minus3
150 times 10minus3
900 117 times 10minus3
116 times 10minus3
117 times 10minus3
111 times 10minus3
1000 860 times 10minus4
858 times 10minus4
855 times 10minus4
824 times 10minus4
119901119901 rarr 119887119892 + 119883
500 740 times 10minus1
739 times 10minus1
721 times 10minus1
516 times 10minus1
600 483 times 10minus1
480 times 10minus1
481 times 10minus1
398 times 10minus1
700 322 times 10minus1
322 times 10minus1
320 times 10minus1
289 times 10minus1
800 224 times 10minus1
221 times 10minus1
221 times 10minus1
204 times 10minus1
900 15 times 10minus1
158 times 10minus1
158 times 10minus1
149 times 10minus1
1000 114 times 10minus1
114 times 10minus1
113 times 10minus1
110 times 10minus1
119901119901 rarr 119887119885 + 119883
500 689 times 10minus2
685 times 10minus2
645 times 10minus2
423 times 10minus2
600 452 times 10minus2
451 times 10minus2
434 times 10minus2
353 times 10minus2
700 312 times 10minus2
311 times 10minus2
305 times 10minus2
265 times 10minus2
800 219 times 10minus2
218 times 10minus2
215 times 10minus2
195 times 10minus2
900 156 times 10minus2
156 times 10minus2
155 times 10minus2
144 times 10minus2
1000 114 times 10minus2
113 times 10minus2
113 times 10minus2
107 times 10minus2
Table 13 The same as Table 11 but for parametrization PIII
SignalMass (GeV)
PIII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887120574 + 119883
500 131 times 10minus2
1314 times 10minus2
1275 times 10minus2
892 times 10minus2
600 859 times 10minus2
858 times 10minus2
844 times 10minus2
703 times 10minus2
700 582 times 10minus2
582 times 10minus2
577 times 10minus2
517 times 10minus2
800 407 times 10minus2
407 times 10minus2
406 times 10minus2
377 times 10minus2
900 292 times 10minus2
292 times 10minus2
291 times 10minus2
277 times 10minus2
1000 214 times 10minus2
213 times 10minus2
213 times 10minus2
206 times 10minus2
119901119901 rarr 119887119892 + 119883
500 1904 times 100
1896 times 100
1843 times 100
1286 times 100
600 1219 times 100
1213 times 100
1193 times 100
992 times 100
700 808 times 100
807 times 100
802 times 100
717 times 100
800 557 times 100
557 times 100
555 times 100
515 times 100
900 394 times 100
394 times 100
394 times 100
374 times 100
1000 285 times 100
285 times 100
285 times 100
274 times 100
119901119901 rarr 119887119885 + 119883
500 176 times 100
175 times 100
165 times 100
105 times 100
600 115 times 100
114 times 100
111 times 100
880 times 10minus1
700 783 times 10minus1
780 times 10minus1
760 times 10minus1
661 times 10minus1
800 547 times 10minus1
541 times 10minus1
531 times 10minus1
480 times 10minus1
900 392 times 10minus1
390 times 10minus1
382 times 10minus1
360 times 10minus1
1000 286 times 10minus1
282 times 10minus1
280 times 10minus1
262 times 10minus1
Advances in High Energy Physics 11
Table 14 The cross sections (in pb) for the backgrounds (119887(119887)119881 119888(119888)119881 and 119895119881 where119881 = photon jet and 119885 boson) with 119901119879cuts on the jets
and photon at the center of mass energy radic119904 = 13TeV
Background 119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887(119887)120574 + 119883 299 times 103
135 times 102
904 times 100
402 times 10minus1
119901119901 rarr 119888(119888)120574 + 119883 187 times 104
815 times 102
540 times 101
243 times 100
119901119901 rarr 119895120574 + 119883 543 times 104
327 times 103
338 times 102
285 times 101
119901119901 rarr 119887(119887)119895 + 119883 783 times 106
305 times 105
192 times 104
893 times 102
119901119901 rarr 119888(119888)119895 + 119883 122 times 107
455 times 105
289 times 104
135 times 103
119901119901 rarr 119895119895 + 119883 243 times 108
854 times 106
544 times 105
280 times 104
119901119901 rarr 119887(119887)119885 + 119883 502 times 102
135 times 102
225 times 101
156 times 100
119901119901 rarr 119888(119888)119885 + 119883 596 times 102
158 times 102
264 times 101
183 times 100
119901119901 rarr 119895119885 + 119883 800 times 103
208 times 103
408 times 102
412 times 101
500 600 700 800 900 1000
Mb998400 (GeV)
10minus1
100
101
102
103
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Figure 13 Integrated luminosity required to reach 3120590 significancefor the signal of 1198871015840 anomalous interactions for parametrization PI atthe LHC withradic119904 = 13TeV
500 600 700 800 900 1000
Mb998400 (GeV)
104
101
102
103
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Figure 14 The same as Figure 13 but for parametrization PII
500 600 700 800 900 100010minus1
100
101
102
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Mb998400 (GeV)
Figure 15 The same as Figure 13 but for parametrization PIII
parameters to include detector effects such as tracking tag-ging efficiencies and smearing effects After the simulationthe typical kinematical distributions are shown in Figures 17-18
In the analysis the signal (with 120581Λ = 03TeVminus1 and1198981198871015840 = 700GeV) and the corresponding background are
taken into account The invariant mass of the new heavyquark 1198871015840 can be reconstructed from a 119887jet and a neutral gaugeboson (where the 119885 boson can also be reconstructed fromits dilepton or hadronic decay) For the 119887120574 production werequire a large 119901120574
119879(gt100GeV) for photon and large 119901119895
119879
(gt100GeV) for jet and pseudorapidity |120578119895120574| (lt25) For the 119887120574signal channel the invariantmass distributions for signal andbackground events are shown in Figure 19The large 119901119895120574
119879and
the requirement of single 119887-tagging allow a better separationof the signal (for 119887120574 channel) from the background and thenwe find a precise limit for the anomalous coupling in thischannel For the 119887119892 and 119887119885 production we require two high119901119879jets (one 119887-jet) and a high 119901
119879jet in addition to the
reconstructed mass 119898rec119885 respectively The main character of
12 Advances in High Energy Physics
500 600 700 800 900 100001
02
03
04
05120581Λ
(TeV
minus1 )
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Mb998400 (GeV)
Figure 16The contour plot of anomalous coupling andmass of newheavy quark 1198871015840 for the dynamical parametrization explained in thetext with a significance of 3120590 atradic119904 = 13TeV and 119871 int = 100fb
minus1
50 100 150 200 250 300 350 400
Entr
ies
0
2000
4000
6000
8000
10000
PhotonJet 1
pT (GeV)
Figure 17 Transverse momentum distributions of leading jet andphoton (119887120574 production) for signal after detector simulation
the signal is the high 119901119895119879andor 119901120574
119879and single 119887-tagged jet
We calculate the signal and background events in the range|119898
rec1198871015840 (GeV) minus 700GeV| lt 50GeV and we find a similar
significance as shown in Figure 16
5 Conclusion
The new heavy quarks of up-type and down-type can be pro-duced with large numbers at the LHC if they have the anoma-lous couplings (via flavor changing neutral current) thatwell dominate over the charged current interactions The
Entr
ies
50 100 150 200 250 300 350 4000
2000
4000
6000
8000
10000
12000
PhotonJet 1
pT (GeV)
Figure 18 Transverse momentum distributions of leading jet andphoton (119895120574 production) for background at the given conditionsmentioned in the text
500 550 600 650 700 750 800 850 900 950 10000
500
1000
1500
2000
2500
3000
BackgroundSignal
Mrecb998400
(GeV)
Even
ts10
GeV
Figure 19The reconstructedmass distributions for background andsignal (119887120574) with119898
1198871015840 = 700GeV and 120581Λ = 03TeVminus1
single production of new heavy quarks can be achievedthrough the anomalous interactions at the LHC with radic119904 =13TeV The anomalous vertices could appear significantly atleading order processes due to the possibility of new heavyquarks From the results of signal significance calculationsfor 1199051015840 (1198871015840) anomalous productions the sensitivity to theanomalous couplings 120581119905
1015840
Λ (1205811198871015840
Λ) can be reached down to010 TeVminus1 (015 TeVminus1) in the lepton + 119887jet + jet +MET (119887jet +jet) channel at radic119904 = 13TeV assuming a dynamical para-metrization for the anomalous couplings and the mass of 750GeV for the new heavy quarks The observability limits onthe anomalous couplings obtained after the simulation arecomparable with the partonic level analysis in the photon and119885 boson associated channels whereas the productions 119905119892 and119887119892 are less comparable due to the fast simulation method In
Advances in High Energy Physics 13
any case the single 119887 tagging will play an important role inprobing new heavy quarks and reducing the background
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgment
This work was supported in part by Turkish Atomic EnergyAuthority (TAEA) under Project Grant no 2011TAEKCERN-A5H2P101-19
References
[1] H J He N Polonsky and S F Su ldquoExtra families Higgs spec-trum and oblique correctionsrdquo Physical Review D vol 64 no5 Article ID 053004 11 pages 2001
[2] B Holdom W S Hou T Hurth M L Mangano S Sultansoyand G Unel ldquoFour statements about the fourth generationrdquoPMC Physics A vol 3 article 4 2009
[3] A Atre M Carena T Han and J Santiago ldquoHeavy quarksabove the top at the Tevatronrdquo Physical ReviewD vol 79 ArticleID 054018 2009
[4] A Atre G Azuelos M Carena et al ldquoModel-independentsearches for new quarks at the LHCrdquo Journal of High EnergyPhysics vol 2011 no 8 article 080 2011
[5] N Chen and H J He ldquoLHC signatures of two-Higgs-doubletswith fourth familyrdquo Journal of High Energy Physics vol 2012article 062 2012
[6] M S Chanowitz ldquoElectroweak constraints on the fourth gener-ation at two loop orderrdquo Physical Review D vol 88 Article ID015012 2013
[7] S Chakdar K Ghosh S Nandi and S K Rai ldquoCollider signa-tures of mirror fermions in the framework of a left-right mirrormodelrdquo Physical Review D vol 88 Article ID 095005 2013
[8] X F Wang C Du and H J He ldquoLHC Higgs signatures fromtopflavor seesaw mechanismrdquo Physics Letters B vol 723 no 4-5 pp 314ndash323 2013
[9] S Bar-Shalom M Geller S Nandi and A Soni ldquoTwo higgsdoublets a 4th generation and a 125GeV higgs a reviewrdquoAdvances in High Energy Physics vol 2013 Article ID 67297228 pages 2013
[10] H Fritzsch and D Holtmannspotter ldquoThe production of singlet-quarks at LEP and HERArdquo Physics Letters B vol 457 no 1ndash3pp 186ndash192 1999
[11] G Aad B Abbott J Abdallah et al ldquoSearch for down-typefourth generation quarks with the ATLAS detector in eventswith one lepton and hadronically decaying119882 bosonsrdquo PhysicalReview Letters vol 109 Article ID 032001 2012
[12] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoSearchfor pair produced fourth-generation up-type quarks in ppcollisions atradic119904 = 7 TeV with a lepton in the final staterdquo PhysicsLetters B vol 718 pp 307ndash328 2012
[13] G Aad B Abbott J Abdallah et al ldquoSearch for pair and singleproduction of new heavy quarks that decay to a Z boson and athird-generation quark in pp collisions at radic119904 = 8TeV with theATLAS detectorrdquo Journal of High Energy Physics vol 2014 no11 article 104 2014
[14] G Aad T Abajyan B Abbott et al ldquoSearch for pair productionof heavy top-like quarks decaying to a high-pTW boson and ab quark in the lepton plus jets final state at radic119904 = 7TeV with theATLAS detectorrdquo Physics Letters B vol 718 no 4ndash5 pp 1284ndash1302 2013
[15] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoSearchfor heavy top-like quark pair production in the dilepton finalstate in pp collisions at radic119904 = 7TeVrdquo Physics Letters B vol 716no 1 pp 103ndash121 2012
[16] G Aad B Abbott J Abdallah et al ldquoSearch for heavy vector-like quarks coupling to light quarks in protonndashproton collisionsat radic119904 = 7 Tev with the ATLAS detectorrdquo Physics Letters B vol712 no 1-2 pp 22ndash39 2012
[17] G Aad T Abajyan B Abbott et al ldquoSearch for a heavy top-quark partner in final states with two leptons with the ATLASdetector at the LHCrdquo Journal of High Energy Physics vol 2012article 94 2012
[18] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoCom-bined search for the quarks of a sequential fourth generationrdquoPhysical Review D vol 86 no 11 Article ID 112003 20 pages2012
[19] R Ciftci ldquoAnomalous single production of the fourth gener-ation quarks at the CERN LHCrdquo Physical Review D vol 78Article ID 075018 2008
[20] I T Cakır H D Yıldız O Cakır and G Unel ldquoAnomalousresonant production of the fourth-family up-type quarks at theLHCrdquo Physical Review D vol 80 Article ID 095009 2009
[21] M Sahin S Sultansoy and S Turkoz ldquoSearching for the fourthfamily quarks through anomalous decaysrdquo Physical Review Dvol 82 no 5 Article ID 051503 2010
[22] M Bobrowski A Lenz J Riedl and J Rohrwild ldquoHow muchspace is left for a new family of fermionsrdquo Physical Review Dvol 79 no 11 Article ID 113006 15 pages 2009
[23] G Eilam B Melic and J Trampetic ldquo119862119875 violation and thefourth generationrdquo Physical Review D vol 80 no 11 Article ID116003 2009
[24] O Cobanoglu E Ozcan S Sultansoy and G Unel ldquoOPUCEMa library with error checkingmechanism for computing obliqueparametersrdquo Computer Physics Communications vol 182 no 8pp 1732ndash1743 2011
[25] T Han and J L Hewett ldquoTop-charm associated production inhigh energy 119890+119890minus collisionsrdquo Physical Review D vol 60 ArticleID 074015 1999
[26] A Belyaev N D Christensen and A Pukhov ldquoCalcHEP 34for collider physics within and beyond the standard modelrdquoComputer Physics Communications vol 184 no 7 pp 1729ndash1769 2013
[27] J Pumplin D Robert Stump J Huston H-L Lai P Nadolskyand W-K Tung ldquoNew generation of Parton distributions withuncertainties from global QCD analysisrdquo Journal of High EnergyPhysics vol 2002 article 012 2002
[28] G L Bayatian S Chatrchyan G Hmayakyan et al ldquoCMSphysics technical design report volume II physics perfor-mancerdquo Journal of Physics G Nuclear and Particle Physics vol34 no 6 p 995 2007
[29] T Sjostrand S Mrenna and P Skands ldquoPYTHIA 64 physicsand manualrdquo Journal of High Energy Physics vol 2006 no 5 p026 2006
[30] J Conway R Culbertson and R Demina Pretty Good Sim-ulation (PGS4) httpwwwphysicsucdavisedusimconwayresearchsoftwarepgspgs4-generalhtm
14 Advances in High Energy Physics
[31] EXROOTANALYSIS package for PGS4 data analysishttpmadgraphhepuiuceduDownloadsExRootAnalysis
[32] R Brun et al An object oriented data analysis framework(ROOT) httpsrootcernchdrupal
[33] F del Aguila and J A Aguilar-Saavedra ldquoMultilepton produc-tion via top flavour-changing neutral couplings at the CERNLHCrdquo Nuclear Physics B vol 576 pp 56ndash84 2000
[34] T Han M Hosch K Whisnant B-L Young and X ZhangldquoSingle top quark production via FCNC couplings at hadroncollidersrdquo Physical Review D vol 58 Article ID 073008 1998
[35] T Stelzer Z Sullivan and S Willenbrock ldquoSingle-top-quarkproduction at hadron collidersrdquoPhysical ReviewD vol 58 no 9Article ID 094021 11 pages 1998
Figure 8The contour plot of anomalous coupling and mass of newheavy quark 1199051015840 for the dynamical parametrization explained in thetext with a significance of 3120590 atradic119904 = 13TeV and 119871 int = 100fb
minus1
50 100 150 200 250 300 350 400
Entr
ies
0
2000
4000
6000
8000
10000
12000
14000
16000
PhotonJet 1
Jet 2Jet 3
pT (GeV)
Figure 9 Transverse momentum distributions of leading jet (Jet 1)and other jets (Jet 2 and Jet 3) and photon for signal (119905120574 production)after detector simulation
systematically the large transverse momentum of photon(119901120574119879gt 100GeV) minimum jet transverse momentum (119901119895
119879gt
20GeV) and the pseudorapidity range (|120578119895120574| lt 25) inaddition to the requirements on mass reconstruction of119882-boson and top quark The large 119901120574
119879and the requirement of
single 119887-tagging allow a better separation of the signal (for 119905120574channel) from the background Other channels for 119905119892 and 119905119885productions are more challenging due to a large number ofjets which require additional discriminators such as angularandor total transverse energy variables However in orderto get rid of the backgrounds from 119882119905 and 119905119905 production
Entr
ies
50 100 150 200 250 300 350 4000
5000
10000
15000
20000
25000
PhotonJet 1
Jet 2Jet 3
pT (GeV)
Figure 10 Transverse momentum distributions of leading jet (Jet1) and other jets (Jet 2 and Jet 3) and photon for background (119882119895120574production)
500 600 700 800 900 1000
40
60
80
100
120
BackgroundSignal
Mrect998400
(GeV)
Even
ts10
GeV
Figure 11The reconstructedmass distributions for background andsignal (119905120574) with119898
1199051015840 = 700GeV and 120581Λ = 015TeVminus1
(for a similar framework the production cross sections areabout 25 pb and 340 pb resp) one can consider the channel3119897 + 119887jet + MET for a distinctive signal from the 1199051015840 rarr 119905119885An analysis of the investigation of single top production withsimilar backgrounds at the LHC can be found in [33ndash35]
42 Analysis of the Process 119901119901 rarr 119887119881 + 119883 (119881 = 119892 119885 120574) for1198871015840 Signal The signal process 119901119901 rarr 119887119881 + 119883 (119881 = 119892 119885 120574)includes the new heavy quark 1198871015840 exchange in both the 119904-channel and the 119905-channel The 119904-channel contributes to thesignal process as resonance around the 1198871015840mass value in the 119887119881invariantmass while the 119905-channel contributes to the nonres-onant behaviour For this process we consider the leptonicdecay of 119885 boson In the analyses we consider the 1198871015840 signalto be 119887jet + 120574 119887jet + 119895 and 119887jet + dilepton
Advances in High Energy Physics 9
Table 11 The cross sections (in pb) for 1198871015840 signal in different decay channel for parametrization PI with 119901119879cuts on the jets and photon and
|120578119895120574| lt 25 at the center of mass energyradic119904 = 13TeV
SignalMass (GeV)
PI119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887120574 + 119883
500 564 times 10minus2
562 times 10minus2
549 times 10minus2
395 times 10minus2
600 396 times 10minus2
396 times 10minus2
390 times 10minus2
333 times 10minus2
700 287 times 10minus2
287 times 10minus2
286 times 10minus2
259 times 10minus2
800 212 times 10minus2
213 times 10minus2
212 times 10minus2
199 times 10minus2
900 160 times 10minus2
160 times 10minus2
160 times 10minus2
153 times 10minus2
1000 122 times 10minus2
122 times 10minus2
122 times 10minus2
119 times 10minus2
119901119901 rarr 119887119892 + 119883
500 813 times 100
813 times 100
793 times 100
596 times 100
600 559 times 100
559 times 100
553 times 100
488 times 100
700 398 times 100
398 times 100
396 times 100
373 times 100
800 291 times 100
291 times 100
290 times 100
281 times 100
900 216 times 100
216 times 100
216 times 100
214 times 100
1000 164 times 100
163 times 100
163 times 100
162 times 100
119901119901 rarr 119887119885 + 119883
500 787 times 10minus1
781 times 10minus1
750 times 10minus1
479 times 10minus1
600 548 times 10minus1
548 times 10minus1
531 times 10minus1
427 times 10minus1
700 395 times 10minus1
394 times 10minus1
386 times 10minus1
339 times 10minus1
800 292 times 10minus1
291 times 10minus1
286 times 10minus1
261 times 10minus1
900 218 times 10minus1
218 times 10minus1
215 times 10minus1
202 times 10minus1
1000 166 times 10minus1
166 times 10minus1
164 times 10minus1
156 times 10minus1
We have obtained the cross sections by using the pseu-dorapidity cuts |120578
119895120574| lt 25 and transverse momentum cuts
119901119895120574
119879gt 20ndash200GeV for jets and photon in Table 11 (Tables
12 and 13) for PI (PII PIII) parametrizations respectivelyInvariantmass distribution of the 119887119881 (where119881 = 120574 119892 and119885)system is shown in Figure 12 for PI parametrization of thesignal with 120581Λ = 02TeVminus1 and 119898
1198871015840 = 700GeV at the
center of mass energy radic119904 = 13TeV It appears from sig-nal significance calculation that the optimized transversemomentum cut is 119901
119879gt 200GeV for 1198871015840 analyses
The backgrounds for the final state 119887(119887)119881 (where 119881 equiv
photon jet and 119885 boson) are given in Table 14 We apply thefollowing cuts to the final state photon and jets as |120578
119895120574| lt 25
and 119901119895120574119879gt 20ndash200GeV It can be noted that the background
cross section decreases as the119901119879cuts increaseWe assume the
efficiency for 119887-tagging to be 120576119887= 50and the rejection ratios
to be 10 for 119888 (119888) quark jets and 1 for light quark jetsIn order to reach 3120590 significance for the signal of 1198871015840
anomalous interactions the required integrated luminosityis shown in Figures 13ndash15 for parametrizations PI PII andPIII at the LHC with radic119904 = 13TeV The channel 1198871015840 rarr 119887120574
requires more integrated luminosity than the other channelsBy requiring the signal significance 119878119878 = 3 the contour plotsof 120581Λ and mass of 1198871015840 quark are presented in Figure 16 Theresults show that one can discover the 1198871015840 quark anomalouscouplings down to 01 in the 119887119892 channel for119898
1198871015840 = 500GeV
500 600 700 800 900 100010minus6
10minus5
10minus4
10minus3
10minus2
10minus1
100
d120590d
mbV
(pb
GeV
)
MbV (GeV)
pp rarr bg + X
pprarr bZ + X
pprarr b120574 + X
Figure 12 Invariant mass distribution of the 119887119881 (where 119881 = 120574 119892and 119885) system is shown in Figure 5 for PI parametrization of thesignal with 120581Λ = 02TeVminus1 and 119898
1198871015840 = 700GeV at the center of
mass energyradic119904 = 13TeV
421 Simulation for 1198871015840 Signal In the simulation we havegenerated 119887119881 (where 119881 = 120574 119892 and 119885) events for each sub-process and these events are simulated using generic detector
10 Advances in High Energy Physics
Table 12 The same as Table 11 but for parametrization PII
SignalMass (GeV)
PII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887120574 + 119883
500 518 times 10minus3
526 times 10minus3
504 times 10minus3
354 times 10minus3
600 338 times 10minus3
337 times 10minus3
336 times 10minus3
277 times 10minus3
700 232 times 10minus3
231 times 10minus3
230 times 10minus3
205 times 10minus3
800 171 times 10minus3
163 times 10minus3
164 times 10minus3
150 times 10minus3
900 117 times 10minus3
116 times 10minus3
117 times 10minus3
111 times 10minus3
1000 860 times 10minus4
858 times 10minus4
855 times 10minus4
824 times 10minus4
119901119901 rarr 119887119892 + 119883
500 740 times 10minus1
739 times 10minus1
721 times 10minus1
516 times 10minus1
600 483 times 10minus1
480 times 10minus1
481 times 10minus1
398 times 10minus1
700 322 times 10minus1
322 times 10minus1
320 times 10minus1
289 times 10minus1
800 224 times 10minus1
221 times 10minus1
221 times 10minus1
204 times 10minus1
900 15 times 10minus1
158 times 10minus1
158 times 10minus1
149 times 10minus1
1000 114 times 10minus1
114 times 10minus1
113 times 10minus1
110 times 10minus1
119901119901 rarr 119887119885 + 119883
500 689 times 10minus2
685 times 10minus2
645 times 10minus2
423 times 10minus2
600 452 times 10minus2
451 times 10minus2
434 times 10minus2
353 times 10minus2
700 312 times 10minus2
311 times 10minus2
305 times 10minus2
265 times 10minus2
800 219 times 10minus2
218 times 10minus2
215 times 10minus2
195 times 10minus2
900 156 times 10minus2
156 times 10minus2
155 times 10minus2
144 times 10minus2
1000 114 times 10minus2
113 times 10minus2
113 times 10minus2
107 times 10minus2
Table 13 The same as Table 11 but for parametrization PIII
SignalMass (GeV)
PIII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887120574 + 119883
500 131 times 10minus2
1314 times 10minus2
1275 times 10minus2
892 times 10minus2
600 859 times 10minus2
858 times 10minus2
844 times 10minus2
703 times 10minus2
700 582 times 10minus2
582 times 10minus2
577 times 10minus2
517 times 10minus2
800 407 times 10minus2
407 times 10minus2
406 times 10minus2
377 times 10minus2
900 292 times 10minus2
292 times 10minus2
291 times 10minus2
277 times 10minus2
1000 214 times 10minus2
213 times 10minus2
213 times 10minus2
206 times 10minus2
119901119901 rarr 119887119892 + 119883
500 1904 times 100
1896 times 100
1843 times 100
1286 times 100
600 1219 times 100
1213 times 100
1193 times 100
992 times 100
700 808 times 100
807 times 100
802 times 100
717 times 100
800 557 times 100
557 times 100
555 times 100
515 times 100
900 394 times 100
394 times 100
394 times 100
374 times 100
1000 285 times 100
285 times 100
285 times 100
274 times 100
119901119901 rarr 119887119885 + 119883
500 176 times 100
175 times 100
165 times 100
105 times 100
600 115 times 100
114 times 100
111 times 100
880 times 10minus1
700 783 times 10minus1
780 times 10minus1
760 times 10minus1
661 times 10minus1
800 547 times 10minus1
541 times 10minus1
531 times 10minus1
480 times 10minus1
900 392 times 10minus1
390 times 10minus1
382 times 10minus1
360 times 10minus1
1000 286 times 10minus1
282 times 10minus1
280 times 10minus1
262 times 10minus1
Advances in High Energy Physics 11
Table 14 The cross sections (in pb) for the backgrounds (119887(119887)119881 119888(119888)119881 and 119895119881 where119881 = photon jet and 119885 boson) with 119901119879cuts on the jets
and photon at the center of mass energy radic119904 = 13TeV
Background 119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887(119887)120574 + 119883 299 times 103
135 times 102
904 times 100
402 times 10minus1
119901119901 rarr 119888(119888)120574 + 119883 187 times 104
815 times 102
540 times 101
243 times 100
119901119901 rarr 119895120574 + 119883 543 times 104
327 times 103
338 times 102
285 times 101
119901119901 rarr 119887(119887)119895 + 119883 783 times 106
305 times 105
192 times 104
893 times 102
119901119901 rarr 119888(119888)119895 + 119883 122 times 107
455 times 105
289 times 104
135 times 103
119901119901 rarr 119895119895 + 119883 243 times 108
854 times 106
544 times 105
280 times 104
119901119901 rarr 119887(119887)119885 + 119883 502 times 102
135 times 102
225 times 101
156 times 100
119901119901 rarr 119888(119888)119885 + 119883 596 times 102
158 times 102
264 times 101
183 times 100
119901119901 rarr 119895119885 + 119883 800 times 103
208 times 103
408 times 102
412 times 101
500 600 700 800 900 1000
Mb998400 (GeV)
10minus1
100
101
102
103
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Figure 13 Integrated luminosity required to reach 3120590 significancefor the signal of 1198871015840 anomalous interactions for parametrization PI atthe LHC withradic119904 = 13TeV
500 600 700 800 900 1000
Mb998400 (GeV)
104
101
102
103
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Figure 14 The same as Figure 13 but for parametrization PII
500 600 700 800 900 100010minus1
100
101
102
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Mb998400 (GeV)
Figure 15 The same as Figure 13 but for parametrization PIII
parameters to include detector effects such as tracking tag-ging efficiencies and smearing effects After the simulationthe typical kinematical distributions are shown in Figures 17-18
In the analysis the signal (with 120581Λ = 03TeVminus1 and1198981198871015840 = 700GeV) and the corresponding background are
taken into account The invariant mass of the new heavyquark 1198871015840 can be reconstructed from a 119887jet and a neutral gaugeboson (where the 119885 boson can also be reconstructed fromits dilepton or hadronic decay) For the 119887120574 production werequire a large 119901120574
119879(gt100GeV) for photon and large 119901119895
119879
(gt100GeV) for jet and pseudorapidity |120578119895120574| (lt25) For the 119887120574signal channel the invariantmass distributions for signal andbackground events are shown in Figure 19The large 119901119895120574
119879and
the requirement of single 119887-tagging allow a better separationof the signal (for 119887120574 channel) from the background and thenwe find a precise limit for the anomalous coupling in thischannel For the 119887119892 and 119887119885 production we require two high119901119879jets (one 119887-jet) and a high 119901
119879jet in addition to the
reconstructed mass 119898rec119885 respectively The main character of
12 Advances in High Energy Physics
500 600 700 800 900 100001
02
03
04
05120581Λ
(TeV
minus1 )
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Mb998400 (GeV)
Figure 16The contour plot of anomalous coupling andmass of newheavy quark 1198871015840 for the dynamical parametrization explained in thetext with a significance of 3120590 atradic119904 = 13TeV and 119871 int = 100fb
minus1
50 100 150 200 250 300 350 400
Entr
ies
0
2000
4000
6000
8000
10000
PhotonJet 1
pT (GeV)
Figure 17 Transverse momentum distributions of leading jet andphoton (119887120574 production) for signal after detector simulation
the signal is the high 119901119895119879andor 119901120574
119879and single 119887-tagged jet
We calculate the signal and background events in the range|119898
rec1198871015840 (GeV) minus 700GeV| lt 50GeV and we find a similar
significance as shown in Figure 16
5 Conclusion
The new heavy quarks of up-type and down-type can be pro-duced with large numbers at the LHC if they have the anoma-lous couplings (via flavor changing neutral current) thatwell dominate over the charged current interactions The
Entr
ies
50 100 150 200 250 300 350 4000
2000
4000
6000
8000
10000
12000
PhotonJet 1
pT (GeV)
Figure 18 Transverse momentum distributions of leading jet andphoton (119895120574 production) for background at the given conditionsmentioned in the text
500 550 600 650 700 750 800 850 900 950 10000
500
1000
1500
2000
2500
3000
BackgroundSignal
Mrecb998400
(GeV)
Even
ts10
GeV
Figure 19The reconstructedmass distributions for background andsignal (119887120574) with119898
1198871015840 = 700GeV and 120581Λ = 03TeVminus1
single production of new heavy quarks can be achievedthrough the anomalous interactions at the LHC with radic119904 =13TeV The anomalous vertices could appear significantly atleading order processes due to the possibility of new heavyquarks From the results of signal significance calculationsfor 1199051015840 (1198871015840) anomalous productions the sensitivity to theanomalous couplings 120581119905
1015840
Λ (1205811198871015840
Λ) can be reached down to010 TeVminus1 (015 TeVminus1) in the lepton + 119887jet + jet +MET (119887jet +jet) channel at radic119904 = 13TeV assuming a dynamical para-metrization for the anomalous couplings and the mass of 750GeV for the new heavy quarks The observability limits onthe anomalous couplings obtained after the simulation arecomparable with the partonic level analysis in the photon and119885 boson associated channels whereas the productions 119905119892 and119887119892 are less comparable due to the fast simulation method In
Advances in High Energy Physics 13
any case the single 119887 tagging will play an important role inprobing new heavy quarks and reducing the background
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgment
This work was supported in part by Turkish Atomic EnergyAuthority (TAEA) under Project Grant no 2011TAEKCERN-A5H2P101-19
References
[1] H J He N Polonsky and S F Su ldquoExtra families Higgs spec-trum and oblique correctionsrdquo Physical Review D vol 64 no5 Article ID 053004 11 pages 2001
[2] B Holdom W S Hou T Hurth M L Mangano S Sultansoyand G Unel ldquoFour statements about the fourth generationrdquoPMC Physics A vol 3 article 4 2009
[3] A Atre M Carena T Han and J Santiago ldquoHeavy quarksabove the top at the Tevatronrdquo Physical ReviewD vol 79 ArticleID 054018 2009
[4] A Atre G Azuelos M Carena et al ldquoModel-independentsearches for new quarks at the LHCrdquo Journal of High EnergyPhysics vol 2011 no 8 article 080 2011
[5] N Chen and H J He ldquoLHC signatures of two-Higgs-doubletswith fourth familyrdquo Journal of High Energy Physics vol 2012article 062 2012
[6] M S Chanowitz ldquoElectroweak constraints on the fourth gener-ation at two loop orderrdquo Physical Review D vol 88 Article ID015012 2013
[7] S Chakdar K Ghosh S Nandi and S K Rai ldquoCollider signa-tures of mirror fermions in the framework of a left-right mirrormodelrdquo Physical Review D vol 88 Article ID 095005 2013
[8] X F Wang C Du and H J He ldquoLHC Higgs signatures fromtopflavor seesaw mechanismrdquo Physics Letters B vol 723 no 4-5 pp 314ndash323 2013
[9] S Bar-Shalom M Geller S Nandi and A Soni ldquoTwo higgsdoublets a 4th generation and a 125GeV higgs a reviewrdquoAdvances in High Energy Physics vol 2013 Article ID 67297228 pages 2013
[10] H Fritzsch and D Holtmannspotter ldquoThe production of singlet-quarks at LEP and HERArdquo Physics Letters B vol 457 no 1ndash3pp 186ndash192 1999
[11] G Aad B Abbott J Abdallah et al ldquoSearch for down-typefourth generation quarks with the ATLAS detector in eventswith one lepton and hadronically decaying119882 bosonsrdquo PhysicalReview Letters vol 109 Article ID 032001 2012
[12] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoSearchfor pair produced fourth-generation up-type quarks in ppcollisions atradic119904 = 7 TeV with a lepton in the final staterdquo PhysicsLetters B vol 718 pp 307ndash328 2012
[13] G Aad B Abbott J Abdallah et al ldquoSearch for pair and singleproduction of new heavy quarks that decay to a Z boson and athird-generation quark in pp collisions at radic119904 = 8TeV with theATLAS detectorrdquo Journal of High Energy Physics vol 2014 no11 article 104 2014
[14] G Aad T Abajyan B Abbott et al ldquoSearch for pair productionof heavy top-like quarks decaying to a high-pTW boson and ab quark in the lepton plus jets final state at radic119904 = 7TeV with theATLAS detectorrdquo Physics Letters B vol 718 no 4ndash5 pp 1284ndash1302 2013
[15] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoSearchfor heavy top-like quark pair production in the dilepton finalstate in pp collisions at radic119904 = 7TeVrdquo Physics Letters B vol 716no 1 pp 103ndash121 2012
[16] G Aad B Abbott J Abdallah et al ldquoSearch for heavy vector-like quarks coupling to light quarks in protonndashproton collisionsat radic119904 = 7 Tev with the ATLAS detectorrdquo Physics Letters B vol712 no 1-2 pp 22ndash39 2012
[17] G Aad T Abajyan B Abbott et al ldquoSearch for a heavy top-quark partner in final states with two leptons with the ATLASdetector at the LHCrdquo Journal of High Energy Physics vol 2012article 94 2012
[18] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoCom-bined search for the quarks of a sequential fourth generationrdquoPhysical Review D vol 86 no 11 Article ID 112003 20 pages2012
[19] R Ciftci ldquoAnomalous single production of the fourth gener-ation quarks at the CERN LHCrdquo Physical Review D vol 78Article ID 075018 2008
[20] I T Cakır H D Yıldız O Cakır and G Unel ldquoAnomalousresonant production of the fourth-family up-type quarks at theLHCrdquo Physical Review D vol 80 Article ID 095009 2009
[21] M Sahin S Sultansoy and S Turkoz ldquoSearching for the fourthfamily quarks through anomalous decaysrdquo Physical Review Dvol 82 no 5 Article ID 051503 2010
[22] M Bobrowski A Lenz J Riedl and J Rohrwild ldquoHow muchspace is left for a new family of fermionsrdquo Physical Review Dvol 79 no 11 Article ID 113006 15 pages 2009
[23] G Eilam B Melic and J Trampetic ldquo119862119875 violation and thefourth generationrdquo Physical Review D vol 80 no 11 Article ID116003 2009
[24] O Cobanoglu E Ozcan S Sultansoy and G Unel ldquoOPUCEMa library with error checkingmechanism for computing obliqueparametersrdquo Computer Physics Communications vol 182 no 8pp 1732ndash1743 2011
[25] T Han and J L Hewett ldquoTop-charm associated production inhigh energy 119890+119890minus collisionsrdquo Physical Review D vol 60 ArticleID 074015 1999
[26] A Belyaev N D Christensen and A Pukhov ldquoCalcHEP 34for collider physics within and beyond the standard modelrdquoComputer Physics Communications vol 184 no 7 pp 1729ndash1769 2013
[27] J Pumplin D Robert Stump J Huston H-L Lai P Nadolskyand W-K Tung ldquoNew generation of Parton distributions withuncertainties from global QCD analysisrdquo Journal of High EnergyPhysics vol 2002 article 012 2002
[28] G L Bayatian S Chatrchyan G Hmayakyan et al ldquoCMSphysics technical design report volume II physics perfor-mancerdquo Journal of Physics G Nuclear and Particle Physics vol34 no 6 p 995 2007
[29] T Sjostrand S Mrenna and P Skands ldquoPYTHIA 64 physicsand manualrdquo Journal of High Energy Physics vol 2006 no 5 p026 2006
[30] J Conway R Culbertson and R Demina Pretty Good Sim-ulation (PGS4) httpwwwphysicsucdavisedusimconwayresearchsoftwarepgspgs4-generalhtm
14 Advances in High Energy Physics
[31] EXROOTANALYSIS package for PGS4 data analysishttpmadgraphhepuiuceduDownloadsExRootAnalysis
[32] R Brun et al An object oriented data analysis framework(ROOT) httpsrootcernchdrupal
[33] F del Aguila and J A Aguilar-Saavedra ldquoMultilepton produc-tion via top flavour-changing neutral couplings at the CERNLHCrdquo Nuclear Physics B vol 576 pp 56ndash84 2000
[34] T Han M Hosch K Whisnant B-L Young and X ZhangldquoSingle top quark production via FCNC couplings at hadroncollidersrdquo Physical Review D vol 58 Article ID 073008 1998
[35] T Stelzer Z Sullivan and S Willenbrock ldquoSingle-top-quarkproduction at hadron collidersrdquoPhysical ReviewD vol 58 no 9Article ID 094021 11 pages 1998
Table 11 The cross sections (in pb) for 1198871015840 signal in different decay channel for parametrization PI with 119901119879cuts on the jets and photon and
|120578119895120574| lt 25 at the center of mass energyradic119904 = 13TeV
SignalMass (GeV)
PI119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887120574 + 119883
500 564 times 10minus2
562 times 10minus2
549 times 10minus2
395 times 10minus2
600 396 times 10minus2
396 times 10minus2
390 times 10minus2
333 times 10minus2
700 287 times 10minus2
287 times 10minus2
286 times 10minus2
259 times 10minus2
800 212 times 10minus2
213 times 10minus2
212 times 10minus2
199 times 10minus2
900 160 times 10minus2
160 times 10minus2
160 times 10minus2
153 times 10minus2
1000 122 times 10minus2
122 times 10minus2
122 times 10minus2
119 times 10minus2
119901119901 rarr 119887119892 + 119883
500 813 times 100
813 times 100
793 times 100
596 times 100
600 559 times 100
559 times 100
553 times 100
488 times 100
700 398 times 100
398 times 100
396 times 100
373 times 100
800 291 times 100
291 times 100
290 times 100
281 times 100
900 216 times 100
216 times 100
216 times 100
214 times 100
1000 164 times 100
163 times 100
163 times 100
162 times 100
119901119901 rarr 119887119885 + 119883
500 787 times 10minus1
781 times 10minus1
750 times 10minus1
479 times 10minus1
600 548 times 10minus1
548 times 10minus1
531 times 10minus1
427 times 10minus1
700 395 times 10minus1
394 times 10minus1
386 times 10minus1
339 times 10minus1
800 292 times 10minus1
291 times 10minus1
286 times 10minus1
261 times 10minus1
900 218 times 10minus1
218 times 10minus1
215 times 10minus1
202 times 10minus1
1000 166 times 10minus1
166 times 10minus1
164 times 10minus1
156 times 10minus1
We have obtained the cross sections by using the pseu-dorapidity cuts |120578
119895120574| lt 25 and transverse momentum cuts
119901119895120574
119879gt 20ndash200GeV for jets and photon in Table 11 (Tables
12 and 13) for PI (PII PIII) parametrizations respectivelyInvariantmass distribution of the 119887119881 (where119881 = 120574 119892 and119885)system is shown in Figure 12 for PI parametrization of thesignal with 120581Λ = 02TeVminus1 and 119898
1198871015840 = 700GeV at the
center of mass energy radic119904 = 13TeV It appears from sig-nal significance calculation that the optimized transversemomentum cut is 119901
119879gt 200GeV for 1198871015840 analyses
The backgrounds for the final state 119887(119887)119881 (where 119881 equiv
photon jet and 119885 boson) are given in Table 14 We apply thefollowing cuts to the final state photon and jets as |120578
119895120574| lt 25
and 119901119895120574119879gt 20ndash200GeV It can be noted that the background
cross section decreases as the119901119879cuts increaseWe assume the
efficiency for 119887-tagging to be 120576119887= 50and the rejection ratios
to be 10 for 119888 (119888) quark jets and 1 for light quark jetsIn order to reach 3120590 significance for the signal of 1198871015840
anomalous interactions the required integrated luminosityis shown in Figures 13ndash15 for parametrizations PI PII andPIII at the LHC with radic119904 = 13TeV The channel 1198871015840 rarr 119887120574
requires more integrated luminosity than the other channelsBy requiring the signal significance 119878119878 = 3 the contour plotsof 120581Λ and mass of 1198871015840 quark are presented in Figure 16 Theresults show that one can discover the 1198871015840 quark anomalouscouplings down to 01 in the 119887119892 channel for119898
1198871015840 = 500GeV
500 600 700 800 900 100010minus6
10minus5
10minus4
10minus3
10minus2
10minus1
100
d120590d
mbV
(pb
GeV
)
MbV (GeV)
pp rarr bg + X
pprarr bZ + X
pprarr b120574 + X
Figure 12 Invariant mass distribution of the 119887119881 (where 119881 = 120574 119892and 119885) system is shown in Figure 5 for PI parametrization of thesignal with 120581Λ = 02TeVminus1 and 119898
1198871015840 = 700GeV at the center of
mass energyradic119904 = 13TeV
421 Simulation for 1198871015840 Signal In the simulation we havegenerated 119887119881 (where 119881 = 120574 119892 and 119885) events for each sub-process and these events are simulated using generic detector
10 Advances in High Energy Physics
Table 12 The same as Table 11 but for parametrization PII
SignalMass (GeV)
PII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887120574 + 119883
500 518 times 10minus3
526 times 10minus3
504 times 10minus3
354 times 10minus3
600 338 times 10minus3
337 times 10minus3
336 times 10minus3
277 times 10minus3
700 232 times 10minus3
231 times 10minus3
230 times 10minus3
205 times 10minus3
800 171 times 10minus3
163 times 10minus3
164 times 10minus3
150 times 10minus3
900 117 times 10minus3
116 times 10minus3
117 times 10minus3
111 times 10minus3
1000 860 times 10minus4
858 times 10minus4
855 times 10minus4
824 times 10minus4
119901119901 rarr 119887119892 + 119883
500 740 times 10minus1
739 times 10minus1
721 times 10minus1
516 times 10minus1
600 483 times 10minus1
480 times 10minus1
481 times 10minus1
398 times 10minus1
700 322 times 10minus1
322 times 10minus1
320 times 10minus1
289 times 10minus1
800 224 times 10minus1
221 times 10minus1
221 times 10minus1
204 times 10minus1
900 15 times 10minus1
158 times 10minus1
158 times 10minus1
149 times 10minus1
1000 114 times 10minus1
114 times 10minus1
113 times 10minus1
110 times 10minus1
119901119901 rarr 119887119885 + 119883
500 689 times 10minus2
685 times 10minus2
645 times 10minus2
423 times 10minus2
600 452 times 10minus2
451 times 10minus2
434 times 10minus2
353 times 10minus2
700 312 times 10minus2
311 times 10minus2
305 times 10minus2
265 times 10minus2
800 219 times 10minus2
218 times 10minus2
215 times 10minus2
195 times 10minus2
900 156 times 10minus2
156 times 10minus2
155 times 10minus2
144 times 10minus2
1000 114 times 10minus2
113 times 10minus2
113 times 10minus2
107 times 10minus2
Table 13 The same as Table 11 but for parametrization PIII
SignalMass (GeV)
PIII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887120574 + 119883
500 131 times 10minus2
1314 times 10minus2
1275 times 10minus2
892 times 10minus2
600 859 times 10minus2
858 times 10minus2
844 times 10minus2
703 times 10minus2
700 582 times 10minus2
582 times 10minus2
577 times 10minus2
517 times 10minus2
800 407 times 10minus2
407 times 10minus2
406 times 10minus2
377 times 10minus2
900 292 times 10minus2
292 times 10minus2
291 times 10minus2
277 times 10minus2
1000 214 times 10minus2
213 times 10minus2
213 times 10minus2
206 times 10minus2
119901119901 rarr 119887119892 + 119883
500 1904 times 100
1896 times 100
1843 times 100
1286 times 100
600 1219 times 100
1213 times 100
1193 times 100
992 times 100
700 808 times 100
807 times 100
802 times 100
717 times 100
800 557 times 100
557 times 100
555 times 100
515 times 100
900 394 times 100
394 times 100
394 times 100
374 times 100
1000 285 times 100
285 times 100
285 times 100
274 times 100
119901119901 rarr 119887119885 + 119883
500 176 times 100
175 times 100
165 times 100
105 times 100
600 115 times 100
114 times 100
111 times 100
880 times 10minus1
700 783 times 10minus1
780 times 10minus1
760 times 10minus1
661 times 10minus1
800 547 times 10minus1
541 times 10minus1
531 times 10minus1
480 times 10minus1
900 392 times 10minus1
390 times 10minus1
382 times 10minus1
360 times 10minus1
1000 286 times 10minus1
282 times 10minus1
280 times 10minus1
262 times 10minus1
Advances in High Energy Physics 11
Table 14 The cross sections (in pb) for the backgrounds (119887(119887)119881 119888(119888)119881 and 119895119881 where119881 = photon jet and 119885 boson) with 119901119879cuts on the jets
and photon at the center of mass energy radic119904 = 13TeV
Background 119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887(119887)120574 + 119883 299 times 103
135 times 102
904 times 100
402 times 10minus1
119901119901 rarr 119888(119888)120574 + 119883 187 times 104
815 times 102
540 times 101
243 times 100
119901119901 rarr 119895120574 + 119883 543 times 104
327 times 103
338 times 102
285 times 101
119901119901 rarr 119887(119887)119895 + 119883 783 times 106
305 times 105
192 times 104
893 times 102
119901119901 rarr 119888(119888)119895 + 119883 122 times 107
455 times 105
289 times 104
135 times 103
119901119901 rarr 119895119895 + 119883 243 times 108
854 times 106
544 times 105
280 times 104
119901119901 rarr 119887(119887)119885 + 119883 502 times 102
135 times 102
225 times 101
156 times 100
119901119901 rarr 119888(119888)119885 + 119883 596 times 102
158 times 102
264 times 101
183 times 100
119901119901 rarr 119895119885 + 119883 800 times 103
208 times 103
408 times 102
412 times 101
500 600 700 800 900 1000
Mb998400 (GeV)
10minus1
100
101
102
103
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Figure 13 Integrated luminosity required to reach 3120590 significancefor the signal of 1198871015840 anomalous interactions for parametrization PI atthe LHC withradic119904 = 13TeV
500 600 700 800 900 1000
Mb998400 (GeV)
104
101
102
103
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Figure 14 The same as Figure 13 but for parametrization PII
500 600 700 800 900 100010minus1
100
101
102
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Mb998400 (GeV)
Figure 15 The same as Figure 13 but for parametrization PIII
parameters to include detector effects such as tracking tag-ging efficiencies and smearing effects After the simulationthe typical kinematical distributions are shown in Figures 17-18
In the analysis the signal (with 120581Λ = 03TeVminus1 and1198981198871015840 = 700GeV) and the corresponding background are
taken into account The invariant mass of the new heavyquark 1198871015840 can be reconstructed from a 119887jet and a neutral gaugeboson (where the 119885 boson can also be reconstructed fromits dilepton or hadronic decay) For the 119887120574 production werequire a large 119901120574
119879(gt100GeV) for photon and large 119901119895
119879
(gt100GeV) for jet and pseudorapidity |120578119895120574| (lt25) For the 119887120574signal channel the invariantmass distributions for signal andbackground events are shown in Figure 19The large 119901119895120574
119879and
the requirement of single 119887-tagging allow a better separationof the signal (for 119887120574 channel) from the background and thenwe find a precise limit for the anomalous coupling in thischannel For the 119887119892 and 119887119885 production we require two high119901119879jets (one 119887-jet) and a high 119901
119879jet in addition to the
reconstructed mass 119898rec119885 respectively The main character of
12 Advances in High Energy Physics
500 600 700 800 900 100001
02
03
04
05120581Λ
(TeV
minus1 )
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Mb998400 (GeV)
Figure 16The contour plot of anomalous coupling andmass of newheavy quark 1198871015840 for the dynamical parametrization explained in thetext with a significance of 3120590 atradic119904 = 13TeV and 119871 int = 100fb
minus1
50 100 150 200 250 300 350 400
Entr
ies
0
2000
4000
6000
8000
10000
PhotonJet 1
pT (GeV)
Figure 17 Transverse momentum distributions of leading jet andphoton (119887120574 production) for signal after detector simulation
the signal is the high 119901119895119879andor 119901120574
119879and single 119887-tagged jet
We calculate the signal and background events in the range|119898
rec1198871015840 (GeV) minus 700GeV| lt 50GeV and we find a similar
significance as shown in Figure 16
5 Conclusion
The new heavy quarks of up-type and down-type can be pro-duced with large numbers at the LHC if they have the anoma-lous couplings (via flavor changing neutral current) thatwell dominate over the charged current interactions The
Entr
ies
50 100 150 200 250 300 350 4000
2000
4000
6000
8000
10000
12000
PhotonJet 1
pT (GeV)
Figure 18 Transverse momentum distributions of leading jet andphoton (119895120574 production) for background at the given conditionsmentioned in the text
500 550 600 650 700 750 800 850 900 950 10000
500
1000
1500
2000
2500
3000
BackgroundSignal
Mrecb998400
(GeV)
Even
ts10
GeV
Figure 19The reconstructedmass distributions for background andsignal (119887120574) with119898
1198871015840 = 700GeV and 120581Λ = 03TeVminus1
single production of new heavy quarks can be achievedthrough the anomalous interactions at the LHC with radic119904 =13TeV The anomalous vertices could appear significantly atleading order processes due to the possibility of new heavyquarks From the results of signal significance calculationsfor 1199051015840 (1198871015840) anomalous productions the sensitivity to theanomalous couplings 120581119905
1015840
Λ (1205811198871015840
Λ) can be reached down to010 TeVminus1 (015 TeVminus1) in the lepton + 119887jet + jet +MET (119887jet +jet) channel at radic119904 = 13TeV assuming a dynamical para-metrization for the anomalous couplings and the mass of 750GeV for the new heavy quarks The observability limits onthe anomalous couplings obtained after the simulation arecomparable with the partonic level analysis in the photon and119885 boson associated channels whereas the productions 119905119892 and119887119892 are less comparable due to the fast simulation method In
Advances in High Energy Physics 13
any case the single 119887 tagging will play an important role inprobing new heavy quarks and reducing the background
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgment
This work was supported in part by Turkish Atomic EnergyAuthority (TAEA) under Project Grant no 2011TAEKCERN-A5H2P101-19
References
[1] H J He N Polonsky and S F Su ldquoExtra families Higgs spec-trum and oblique correctionsrdquo Physical Review D vol 64 no5 Article ID 053004 11 pages 2001
[2] B Holdom W S Hou T Hurth M L Mangano S Sultansoyand G Unel ldquoFour statements about the fourth generationrdquoPMC Physics A vol 3 article 4 2009
[3] A Atre M Carena T Han and J Santiago ldquoHeavy quarksabove the top at the Tevatronrdquo Physical ReviewD vol 79 ArticleID 054018 2009
[4] A Atre G Azuelos M Carena et al ldquoModel-independentsearches for new quarks at the LHCrdquo Journal of High EnergyPhysics vol 2011 no 8 article 080 2011
[5] N Chen and H J He ldquoLHC signatures of two-Higgs-doubletswith fourth familyrdquo Journal of High Energy Physics vol 2012article 062 2012
[6] M S Chanowitz ldquoElectroweak constraints on the fourth gener-ation at two loop orderrdquo Physical Review D vol 88 Article ID015012 2013
[7] S Chakdar K Ghosh S Nandi and S K Rai ldquoCollider signa-tures of mirror fermions in the framework of a left-right mirrormodelrdquo Physical Review D vol 88 Article ID 095005 2013
[8] X F Wang C Du and H J He ldquoLHC Higgs signatures fromtopflavor seesaw mechanismrdquo Physics Letters B vol 723 no 4-5 pp 314ndash323 2013
[9] S Bar-Shalom M Geller S Nandi and A Soni ldquoTwo higgsdoublets a 4th generation and a 125GeV higgs a reviewrdquoAdvances in High Energy Physics vol 2013 Article ID 67297228 pages 2013
[10] H Fritzsch and D Holtmannspotter ldquoThe production of singlet-quarks at LEP and HERArdquo Physics Letters B vol 457 no 1ndash3pp 186ndash192 1999
[11] G Aad B Abbott J Abdallah et al ldquoSearch for down-typefourth generation quarks with the ATLAS detector in eventswith one lepton and hadronically decaying119882 bosonsrdquo PhysicalReview Letters vol 109 Article ID 032001 2012
[12] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoSearchfor pair produced fourth-generation up-type quarks in ppcollisions atradic119904 = 7 TeV with a lepton in the final staterdquo PhysicsLetters B vol 718 pp 307ndash328 2012
[13] G Aad B Abbott J Abdallah et al ldquoSearch for pair and singleproduction of new heavy quarks that decay to a Z boson and athird-generation quark in pp collisions at radic119904 = 8TeV with theATLAS detectorrdquo Journal of High Energy Physics vol 2014 no11 article 104 2014
[14] G Aad T Abajyan B Abbott et al ldquoSearch for pair productionof heavy top-like quarks decaying to a high-pTW boson and ab quark in the lepton plus jets final state at radic119904 = 7TeV with theATLAS detectorrdquo Physics Letters B vol 718 no 4ndash5 pp 1284ndash1302 2013
[15] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoSearchfor heavy top-like quark pair production in the dilepton finalstate in pp collisions at radic119904 = 7TeVrdquo Physics Letters B vol 716no 1 pp 103ndash121 2012
[16] G Aad B Abbott J Abdallah et al ldquoSearch for heavy vector-like quarks coupling to light quarks in protonndashproton collisionsat radic119904 = 7 Tev with the ATLAS detectorrdquo Physics Letters B vol712 no 1-2 pp 22ndash39 2012
[17] G Aad T Abajyan B Abbott et al ldquoSearch for a heavy top-quark partner in final states with two leptons with the ATLASdetector at the LHCrdquo Journal of High Energy Physics vol 2012article 94 2012
[18] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoCom-bined search for the quarks of a sequential fourth generationrdquoPhysical Review D vol 86 no 11 Article ID 112003 20 pages2012
[19] R Ciftci ldquoAnomalous single production of the fourth gener-ation quarks at the CERN LHCrdquo Physical Review D vol 78Article ID 075018 2008
[20] I T Cakır H D Yıldız O Cakır and G Unel ldquoAnomalousresonant production of the fourth-family up-type quarks at theLHCrdquo Physical Review D vol 80 Article ID 095009 2009
[21] M Sahin S Sultansoy and S Turkoz ldquoSearching for the fourthfamily quarks through anomalous decaysrdquo Physical Review Dvol 82 no 5 Article ID 051503 2010
[22] M Bobrowski A Lenz J Riedl and J Rohrwild ldquoHow muchspace is left for a new family of fermionsrdquo Physical Review Dvol 79 no 11 Article ID 113006 15 pages 2009
[23] G Eilam B Melic and J Trampetic ldquo119862119875 violation and thefourth generationrdquo Physical Review D vol 80 no 11 Article ID116003 2009
[24] O Cobanoglu E Ozcan S Sultansoy and G Unel ldquoOPUCEMa library with error checkingmechanism for computing obliqueparametersrdquo Computer Physics Communications vol 182 no 8pp 1732ndash1743 2011
[25] T Han and J L Hewett ldquoTop-charm associated production inhigh energy 119890+119890minus collisionsrdquo Physical Review D vol 60 ArticleID 074015 1999
[26] A Belyaev N D Christensen and A Pukhov ldquoCalcHEP 34for collider physics within and beyond the standard modelrdquoComputer Physics Communications vol 184 no 7 pp 1729ndash1769 2013
[27] J Pumplin D Robert Stump J Huston H-L Lai P Nadolskyand W-K Tung ldquoNew generation of Parton distributions withuncertainties from global QCD analysisrdquo Journal of High EnergyPhysics vol 2002 article 012 2002
[28] G L Bayatian S Chatrchyan G Hmayakyan et al ldquoCMSphysics technical design report volume II physics perfor-mancerdquo Journal of Physics G Nuclear and Particle Physics vol34 no 6 p 995 2007
[29] T Sjostrand S Mrenna and P Skands ldquoPYTHIA 64 physicsand manualrdquo Journal of High Energy Physics vol 2006 no 5 p026 2006
[30] J Conway R Culbertson and R Demina Pretty Good Sim-ulation (PGS4) httpwwwphysicsucdavisedusimconwayresearchsoftwarepgspgs4-generalhtm
14 Advances in High Energy Physics
[31] EXROOTANALYSIS package for PGS4 data analysishttpmadgraphhepuiuceduDownloadsExRootAnalysis
[32] R Brun et al An object oriented data analysis framework(ROOT) httpsrootcernchdrupal
[33] F del Aguila and J A Aguilar-Saavedra ldquoMultilepton produc-tion via top flavour-changing neutral couplings at the CERNLHCrdquo Nuclear Physics B vol 576 pp 56ndash84 2000
[34] T Han M Hosch K Whisnant B-L Young and X ZhangldquoSingle top quark production via FCNC couplings at hadroncollidersrdquo Physical Review D vol 58 Article ID 073008 1998
[35] T Stelzer Z Sullivan and S Willenbrock ldquoSingle-top-quarkproduction at hadron collidersrdquoPhysical ReviewD vol 58 no 9Article ID 094021 11 pages 1998
Table 12 The same as Table 11 but for parametrization PII
SignalMass (GeV)
PII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887120574 + 119883
500 518 times 10minus3
526 times 10minus3
504 times 10minus3
354 times 10minus3
600 338 times 10minus3
337 times 10minus3
336 times 10minus3
277 times 10minus3
700 232 times 10minus3
231 times 10minus3
230 times 10minus3
205 times 10minus3
800 171 times 10minus3
163 times 10minus3
164 times 10minus3
150 times 10minus3
900 117 times 10minus3
116 times 10minus3
117 times 10minus3
111 times 10minus3
1000 860 times 10minus4
858 times 10minus4
855 times 10minus4
824 times 10minus4
119901119901 rarr 119887119892 + 119883
500 740 times 10minus1
739 times 10minus1
721 times 10minus1
516 times 10minus1
600 483 times 10minus1
480 times 10minus1
481 times 10minus1
398 times 10minus1
700 322 times 10minus1
322 times 10minus1
320 times 10minus1
289 times 10minus1
800 224 times 10minus1
221 times 10minus1
221 times 10minus1
204 times 10minus1
900 15 times 10minus1
158 times 10minus1
158 times 10minus1
149 times 10minus1
1000 114 times 10minus1
114 times 10minus1
113 times 10minus1
110 times 10minus1
119901119901 rarr 119887119885 + 119883
500 689 times 10minus2
685 times 10minus2
645 times 10minus2
423 times 10minus2
600 452 times 10minus2
451 times 10minus2
434 times 10minus2
353 times 10minus2
700 312 times 10minus2
311 times 10minus2
305 times 10minus2
265 times 10minus2
800 219 times 10minus2
218 times 10minus2
215 times 10minus2
195 times 10minus2
900 156 times 10minus2
156 times 10minus2
155 times 10minus2
144 times 10minus2
1000 114 times 10minus2
113 times 10minus2
113 times 10minus2
107 times 10minus2
Table 13 The same as Table 11 but for parametrization PIII
SignalMass (GeV)
PIII119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887120574 + 119883
500 131 times 10minus2
1314 times 10minus2
1275 times 10minus2
892 times 10minus2
600 859 times 10minus2
858 times 10minus2
844 times 10minus2
703 times 10minus2
700 582 times 10minus2
582 times 10minus2
577 times 10minus2
517 times 10minus2
800 407 times 10minus2
407 times 10minus2
406 times 10minus2
377 times 10minus2
900 292 times 10minus2
292 times 10minus2
291 times 10minus2
277 times 10minus2
1000 214 times 10minus2
213 times 10minus2
213 times 10minus2
206 times 10minus2
119901119901 rarr 119887119892 + 119883
500 1904 times 100
1896 times 100
1843 times 100
1286 times 100
600 1219 times 100
1213 times 100
1193 times 100
992 times 100
700 808 times 100
807 times 100
802 times 100
717 times 100
800 557 times 100
557 times 100
555 times 100
515 times 100
900 394 times 100
394 times 100
394 times 100
374 times 100
1000 285 times 100
285 times 100
285 times 100
274 times 100
119901119901 rarr 119887119885 + 119883
500 176 times 100
175 times 100
165 times 100
105 times 100
600 115 times 100
114 times 100
111 times 100
880 times 10minus1
700 783 times 10minus1
780 times 10minus1
760 times 10minus1
661 times 10minus1
800 547 times 10minus1
541 times 10minus1
531 times 10minus1
480 times 10minus1
900 392 times 10minus1
390 times 10minus1
382 times 10minus1
360 times 10minus1
1000 286 times 10minus1
282 times 10minus1
280 times 10minus1
262 times 10minus1
Advances in High Energy Physics 11
Table 14 The cross sections (in pb) for the backgrounds (119887(119887)119881 119888(119888)119881 and 119895119881 where119881 = photon jet and 119885 boson) with 119901119879cuts on the jets
and photon at the center of mass energy radic119904 = 13TeV
Background 119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887(119887)120574 + 119883 299 times 103
135 times 102
904 times 100
402 times 10minus1
119901119901 rarr 119888(119888)120574 + 119883 187 times 104
815 times 102
540 times 101
243 times 100
119901119901 rarr 119895120574 + 119883 543 times 104
327 times 103
338 times 102
285 times 101
119901119901 rarr 119887(119887)119895 + 119883 783 times 106
305 times 105
192 times 104
893 times 102
119901119901 rarr 119888(119888)119895 + 119883 122 times 107
455 times 105
289 times 104
135 times 103
119901119901 rarr 119895119895 + 119883 243 times 108
854 times 106
544 times 105
280 times 104
119901119901 rarr 119887(119887)119885 + 119883 502 times 102
135 times 102
225 times 101
156 times 100
119901119901 rarr 119888(119888)119885 + 119883 596 times 102
158 times 102
264 times 101
183 times 100
119901119901 rarr 119895119885 + 119883 800 times 103
208 times 103
408 times 102
412 times 101
500 600 700 800 900 1000
Mb998400 (GeV)
10minus1
100
101
102
103
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Figure 13 Integrated luminosity required to reach 3120590 significancefor the signal of 1198871015840 anomalous interactions for parametrization PI atthe LHC withradic119904 = 13TeV
500 600 700 800 900 1000
Mb998400 (GeV)
104
101
102
103
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Figure 14 The same as Figure 13 but for parametrization PII
500 600 700 800 900 100010minus1
100
101
102
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Mb998400 (GeV)
Figure 15 The same as Figure 13 but for parametrization PIII
parameters to include detector effects such as tracking tag-ging efficiencies and smearing effects After the simulationthe typical kinematical distributions are shown in Figures 17-18
In the analysis the signal (with 120581Λ = 03TeVminus1 and1198981198871015840 = 700GeV) and the corresponding background are
taken into account The invariant mass of the new heavyquark 1198871015840 can be reconstructed from a 119887jet and a neutral gaugeboson (where the 119885 boson can also be reconstructed fromits dilepton or hadronic decay) For the 119887120574 production werequire a large 119901120574
119879(gt100GeV) for photon and large 119901119895
119879
(gt100GeV) for jet and pseudorapidity |120578119895120574| (lt25) For the 119887120574signal channel the invariantmass distributions for signal andbackground events are shown in Figure 19The large 119901119895120574
119879and
the requirement of single 119887-tagging allow a better separationof the signal (for 119887120574 channel) from the background and thenwe find a precise limit for the anomalous coupling in thischannel For the 119887119892 and 119887119885 production we require two high119901119879jets (one 119887-jet) and a high 119901
119879jet in addition to the
reconstructed mass 119898rec119885 respectively The main character of
12 Advances in High Energy Physics
500 600 700 800 900 100001
02
03
04
05120581Λ
(TeV
minus1 )
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Mb998400 (GeV)
Figure 16The contour plot of anomalous coupling andmass of newheavy quark 1198871015840 for the dynamical parametrization explained in thetext with a significance of 3120590 atradic119904 = 13TeV and 119871 int = 100fb
minus1
50 100 150 200 250 300 350 400
Entr
ies
0
2000
4000
6000
8000
10000
PhotonJet 1
pT (GeV)
Figure 17 Transverse momentum distributions of leading jet andphoton (119887120574 production) for signal after detector simulation
the signal is the high 119901119895119879andor 119901120574
119879and single 119887-tagged jet
We calculate the signal and background events in the range|119898
rec1198871015840 (GeV) minus 700GeV| lt 50GeV and we find a similar
significance as shown in Figure 16
5 Conclusion
The new heavy quarks of up-type and down-type can be pro-duced with large numbers at the LHC if they have the anoma-lous couplings (via flavor changing neutral current) thatwell dominate over the charged current interactions The
Entr
ies
50 100 150 200 250 300 350 4000
2000
4000
6000
8000
10000
12000
PhotonJet 1
pT (GeV)
Figure 18 Transverse momentum distributions of leading jet andphoton (119895120574 production) for background at the given conditionsmentioned in the text
500 550 600 650 700 750 800 850 900 950 10000
500
1000
1500
2000
2500
3000
BackgroundSignal
Mrecb998400
(GeV)
Even
ts10
GeV
Figure 19The reconstructedmass distributions for background andsignal (119887120574) with119898
1198871015840 = 700GeV and 120581Λ = 03TeVminus1
single production of new heavy quarks can be achievedthrough the anomalous interactions at the LHC with radic119904 =13TeV The anomalous vertices could appear significantly atleading order processes due to the possibility of new heavyquarks From the results of signal significance calculationsfor 1199051015840 (1198871015840) anomalous productions the sensitivity to theanomalous couplings 120581119905
1015840
Λ (1205811198871015840
Λ) can be reached down to010 TeVminus1 (015 TeVminus1) in the lepton + 119887jet + jet +MET (119887jet +jet) channel at radic119904 = 13TeV assuming a dynamical para-metrization for the anomalous couplings and the mass of 750GeV for the new heavy quarks The observability limits onthe anomalous couplings obtained after the simulation arecomparable with the partonic level analysis in the photon and119885 boson associated channels whereas the productions 119905119892 and119887119892 are less comparable due to the fast simulation method In
Advances in High Energy Physics 13
any case the single 119887 tagging will play an important role inprobing new heavy quarks and reducing the background
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgment
This work was supported in part by Turkish Atomic EnergyAuthority (TAEA) under Project Grant no 2011TAEKCERN-A5H2P101-19
References
[1] H J He N Polonsky and S F Su ldquoExtra families Higgs spec-trum and oblique correctionsrdquo Physical Review D vol 64 no5 Article ID 053004 11 pages 2001
[2] B Holdom W S Hou T Hurth M L Mangano S Sultansoyand G Unel ldquoFour statements about the fourth generationrdquoPMC Physics A vol 3 article 4 2009
[3] A Atre M Carena T Han and J Santiago ldquoHeavy quarksabove the top at the Tevatronrdquo Physical ReviewD vol 79 ArticleID 054018 2009
[4] A Atre G Azuelos M Carena et al ldquoModel-independentsearches for new quarks at the LHCrdquo Journal of High EnergyPhysics vol 2011 no 8 article 080 2011
[5] N Chen and H J He ldquoLHC signatures of two-Higgs-doubletswith fourth familyrdquo Journal of High Energy Physics vol 2012article 062 2012
[6] M S Chanowitz ldquoElectroweak constraints on the fourth gener-ation at two loop orderrdquo Physical Review D vol 88 Article ID015012 2013
[7] S Chakdar K Ghosh S Nandi and S K Rai ldquoCollider signa-tures of mirror fermions in the framework of a left-right mirrormodelrdquo Physical Review D vol 88 Article ID 095005 2013
[8] X F Wang C Du and H J He ldquoLHC Higgs signatures fromtopflavor seesaw mechanismrdquo Physics Letters B vol 723 no 4-5 pp 314ndash323 2013
[9] S Bar-Shalom M Geller S Nandi and A Soni ldquoTwo higgsdoublets a 4th generation and a 125GeV higgs a reviewrdquoAdvances in High Energy Physics vol 2013 Article ID 67297228 pages 2013
[10] H Fritzsch and D Holtmannspotter ldquoThe production of singlet-quarks at LEP and HERArdquo Physics Letters B vol 457 no 1ndash3pp 186ndash192 1999
[11] G Aad B Abbott J Abdallah et al ldquoSearch for down-typefourth generation quarks with the ATLAS detector in eventswith one lepton and hadronically decaying119882 bosonsrdquo PhysicalReview Letters vol 109 Article ID 032001 2012
[12] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoSearchfor pair produced fourth-generation up-type quarks in ppcollisions atradic119904 = 7 TeV with a lepton in the final staterdquo PhysicsLetters B vol 718 pp 307ndash328 2012
[13] G Aad B Abbott J Abdallah et al ldquoSearch for pair and singleproduction of new heavy quarks that decay to a Z boson and athird-generation quark in pp collisions at radic119904 = 8TeV with theATLAS detectorrdquo Journal of High Energy Physics vol 2014 no11 article 104 2014
[14] G Aad T Abajyan B Abbott et al ldquoSearch for pair productionof heavy top-like quarks decaying to a high-pTW boson and ab quark in the lepton plus jets final state at radic119904 = 7TeV with theATLAS detectorrdquo Physics Letters B vol 718 no 4ndash5 pp 1284ndash1302 2013
[15] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoSearchfor heavy top-like quark pair production in the dilepton finalstate in pp collisions at radic119904 = 7TeVrdquo Physics Letters B vol 716no 1 pp 103ndash121 2012
[16] G Aad B Abbott J Abdallah et al ldquoSearch for heavy vector-like quarks coupling to light quarks in protonndashproton collisionsat radic119904 = 7 Tev with the ATLAS detectorrdquo Physics Letters B vol712 no 1-2 pp 22ndash39 2012
[17] G Aad T Abajyan B Abbott et al ldquoSearch for a heavy top-quark partner in final states with two leptons with the ATLASdetector at the LHCrdquo Journal of High Energy Physics vol 2012article 94 2012
[18] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoCom-bined search for the quarks of a sequential fourth generationrdquoPhysical Review D vol 86 no 11 Article ID 112003 20 pages2012
[19] R Ciftci ldquoAnomalous single production of the fourth gener-ation quarks at the CERN LHCrdquo Physical Review D vol 78Article ID 075018 2008
[20] I T Cakır H D Yıldız O Cakır and G Unel ldquoAnomalousresonant production of the fourth-family up-type quarks at theLHCrdquo Physical Review D vol 80 Article ID 095009 2009
[21] M Sahin S Sultansoy and S Turkoz ldquoSearching for the fourthfamily quarks through anomalous decaysrdquo Physical Review Dvol 82 no 5 Article ID 051503 2010
[22] M Bobrowski A Lenz J Riedl and J Rohrwild ldquoHow muchspace is left for a new family of fermionsrdquo Physical Review Dvol 79 no 11 Article ID 113006 15 pages 2009
[23] G Eilam B Melic and J Trampetic ldquo119862119875 violation and thefourth generationrdquo Physical Review D vol 80 no 11 Article ID116003 2009
[24] O Cobanoglu E Ozcan S Sultansoy and G Unel ldquoOPUCEMa library with error checkingmechanism for computing obliqueparametersrdquo Computer Physics Communications vol 182 no 8pp 1732ndash1743 2011
[25] T Han and J L Hewett ldquoTop-charm associated production inhigh energy 119890+119890minus collisionsrdquo Physical Review D vol 60 ArticleID 074015 1999
[26] A Belyaev N D Christensen and A Pukhov ldquoCalcHEP 34for collider physics within and beyond the standard modelrdquoComputer Physics Communications vol 184 no 7 pp 1729ndash1769 2013
[27] J Pumplin D Robert Stump J Huston H-L Lai P Nadolskyand W-K Tung ldquoNew generation of Parton distributions withuncertainties from global QCD analysisrdquo Journal of High EnergyPhysics vol 2002 article 012 2002
[28] G L Bayatian S Chatrchyan G Hmayakyan et al ldquoCMSphysics technical design report volume II physics perfor-mancerdquo Journal of Physics G Nuclear and Particle Physics vol34 no 6 p 995 2007
[29] T Sjostrand S Mrenna and P Skands ldquoPYTHIA 64 physicsand manualrdquo Journal of High Energy Physics vol 2006 no 5 p026 2006
[30] J Conway R Culbertson and R Demina Pretty Good Sim-ulation (PGS4) httpwwwphysicsucdavisedusimconwayresearchsoftwarepgspgs4-generalhtm
14 Advances in High Energy Physics
[31] EXROOTANALYSIS package for PGS4 data analysishttpmadgraphhepuiuceduDownloadsExRootAnalysis
[32] R Brun et al An object oriented data analysis framework(ROOT) httpsrootcernchdrupal
[33] F del Aguila and J A Aguilar-Saavedra ldquoMultilepton produc-tion via top flavour-changing neutral couplings at the CERNLHCrdquo Nuclear Physics B vol 576 pp 56ndash84 2000
[34] T Han M Hosch K Whisnant B-L Young and X ZhangldquoSingle top quark production via FCNC couplings at hadroncollidersrdquo Physical Review D vol 58 Article ID 073008 1998
[35] T Stelzer Z Sullivan and S Willenbrock ldquoSingle-top-quarkproduction at hadron collidersrdquoPhysical ReviewD vol 58 no 9Article ID 094021 11 pages 1998
Table 14 The cross sections (in pb) for the backgrounds (119887(119887)119881 119888(119888)119881 and 119895119881 where119881 = photon jet and 119885 boson) with 119901119879cuts on the jets
and photon at the center of mass energy radic119904 = 13TeV
Background 119901119879gt 20GeV 119901
119879gt 50GeV 119901
119879gt 100GeV 119901
119879gt 200GeV
119901119901 rarr 119887(119887)120574 + 119883 299 times 103
135 times 102
904 times 100
402 times 10minus1
119901119901 rarr 119888(119888)120574 + 119883 187 times 104
815 times 102
540 times 101
243 times 100
119901119901 rarr 119895120574 + 119883 543 times 104
327 times 103
338 times 102
285 times 101
119901119901 rarr 119887(119887)119895 + 119883 783 times 106
305 times 105
192 times 104
893 times 102
119901119901 rarr 119888(119888)119895 + 119883 122 times 107
455 times 105
289 times 104
135 times 103
119901119901 rarr 119895119895 + 119883 243 times 108
854 times 106
544 times 105
280 times 104
119901119901 rarr 119887(119887)119885 + 119883 502 times 102
135 times 102
225 times 101
156 times 100
119901119901 rarr 119888(119888)119885 + 119883 596 times 102
158 times 102
264 times 101
183 times 100
119901119901 rarr 119895119885 + 119883 800 times 103
208 times 103
408 times 102
412 times 101
500 600 700 800 900 1000
Mb998400 (GeV)
10minus1
100
101
102
103
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Figure 13 Integrated luminosity required to reach 3120590 significancefor the signal of 1198871015840 anomalous interactions for parametrization PI atthe LHC withradic119904 = 13TeV
500 600 700 800 900 1000
Mb998400 (GeV)
104
101
102
103
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Figure 14 The same as Figure 13 but for parametrization PII
500 600 700 800 900 100010minus1
100
101
102
Lin
t(fb
minus1)
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Mb998400 (GeV)
Figure 15 The same as Figure 13 but for parametrization PIII
parameters to include detector effects such as tracking tag-ging efficiencies and smearing effects After the simulationthe typical kinematical distributions are shown in Figures 17-18
In the analysis the signal (with 120581Λ = 03TeVminus1 and1198981198871015840 = 700GeV) and the corresponding background are
taken into account The invariant mass of the new heavyquark 1198871015840 can be reconstructed from a 119887jet and a neutral gaugeboson (where the 119885 boson can also be reconstructed fromits dilepton or hadronic decay) For the 119887120574 production werequire a large 119901120574
119879(gt100GeV) for photon and large 119901119895
119879
(gt100GeV) for jet and pseudorapidity |120578119895120574| (lt25) For the 119887120574signal channel the invariantmass distributions for signal andbackground events are shown in Figure 19The large 119901119895120574
119879and
the requirement of single 119887-tagging allow a better separationof the signal (for 119887120574 channel) from the background and thenwe find a precise limit for the anomalous coupling in thischannel For the 119887119892 and 119887119885 production we require two high119901119879jets (one 119887-jet) and a high 119901
119879jet in addition to the
reconstructed mass 119898rec119885 respectively The main character of
12 Advances in High Energy Physics
500 600 700 800 900 100001
02
03
04
05120581Λ
(TeV
minus1 )
b998400 rarr b120574
b998400 rarr bZ
b998400 rarr bg
Mb998400 (GeV)
Figure 16The contour plot of anomalous coupling andmass of newheavy quark 1198871015840 for the dynamical parametrization explained in thetext with a significance of 3120590 atradic119904 = 13TeV and 119871 int = 100fb
minus1
50 100 150 200 250 300 350 400
Entr
ies
0
2000
4000
6000
8000
10000
PhotonJet 1
pT (GeV)
Figure 17 Transverse momentum distributions of leading jet andphoton (119887120574 production) for signal after detector simulation
the signal is the high 119901119895119879andor 119901120574
119879and single 119887-tagged jet
We calculate the signal and background events in the range|119898
rec1198871015840 (GeV) minus 700GeV| lt 50GeV and we find a similar
significance as shown in Figure 16
5 Conclusion
The new heavy quarks of up-type and down-type can be pro-duced with large numbers at the LHC if they have the anoma-lous couplings (via flavor changing neutral current) thatwell dominate over the charged current interactions The
Entr
ies
50 100 150 200 250 300 350 4000
2000
4000
6000
8000
10000
12000
PhotonJet 1
pT (GeV)
Figure 18 Transverse momentum distributions of leading jet andphoton (119895120574 production) for background at the given conditionsmentioned in the text
500 550 600 650 700 750 800 850 900 950 10000
500
1000
1500
2000
2500
3000
BackgroundSignal
Mrecb998400
(GeV)
Even
ts10
GeV
Figure 19The reconstructedmass distributions for background andsignal (119887120574) with119898
1198871015840 = 700GeV and 120581Λ = 03TeVminus1
single production of new heavy quarks can be achievedthrough the anomalous interactions at the LHC with radic119904 =13TeV The anomalous vertices could appear significantly atleading order processes due to the possibility of new heavyquarks From the results of signal significance calculationsfor 1199051015840 (1198871015840) anomalous productions the sensitivity to theanomalous couplings 120581119905
1015840
Λ (1205811198871015840
Λ) can be reached down to010 TeVminus1 (015 TeVminus1) in the lepton + 119887jet + jet +MET (119887jet +jet) channel at radic119904 = 13TeV assuming a dynamical para-metrization for the anomalous couplings and the mass of 750GeV for the new heavy quarks The observability limits onthe anomalous couplings obtained after the simulation arecomparable with the partonic level analysis in the photon and119885 boson associated channels whereas the productions 119905119892 and119887119892 are less comparable due to the fast simulation method In
Advances in High Energy Physics 13
any case the single 119887 tagging will play an important role inprobing new heavy quarks and reducing the background
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgment
This work was supported in part by Turkish Atomic EnergyAuthority (TAEA) under Project Grant no 2011TAEKCERN-A5H2P101-19
References
[1] H J He N Polonsky and S F Su ldquoExtra families Higgs spec-trum and oblique correctionsrdquo Physical Review D vol 64 no5 Article ID 053004 11 pages 2001
[2] B Holdom W S Hou T Hurth M L Mangano S Sultansoyand G Unel ldquoFour statements about the fourth generationrdquoPMC Physics A vol 3 article 4 2009
[3] A Atre M Carena T Han and J Santiago ldquoHeavy quarksabove the top at the Tevatronrdquo Physical ReviewD vol 79 ArticleID 054018 2009
[4] A Atre G Azuelos M Carena et al ldquoModel-independentsearches for new quarks at the LHCrdquo Journal of High EnergyPhysics vol 2011 no 8 article 080 2011
[5] N Chen and H J He ldquoLHC signatures of two-Higgs-doubletswith fourth familyrdquo Journal of High Energy Physics vol 2012article 062 2012
[6] M S Chanowitz ldquoElectroweak constraints on the fourth gener-ation at two loop orderrdquo Physical Review D vol 88 Article ID015012 2013
[7] S Chakdar K Ghosh S Nandi and S K Rai ldquoCollider signa-tures of mirror fermions in the framework of a left-right mirrormodelrdquo Physical Review D vol 88 Article ID 095005 2013
[8] X F Wang C Du and H J He ldquoLHC Higgs signatures fromtopflavor seesaw mechanismrdquo Physics Letters B vol 723 no 4-5 pp 314ndash323 2013
[9] S Bar-Shalom M Geller S Nandi and A Soni ldquoTwo higgsdoublets a 4th generation and a 125GeV higgs a reviewrdquoAdvances in High Energy Physics vol 2013 Article ID 67297228 pages 2013
[10] H Fritzsch and D Holtmannspotter ldquoThe production of singlet-quarks at LEP and HERArdquo Physics Letters B vol 457 no 1ndash3pp 186ndash192 1999
[11] G Aad B Abbott J Abdallah et al ldquoSearch for down-typefourth generation quarks with the ATLAS detector in eventswith one lepton and hadronically decaying119882 bosonsrdquo PhysicalReview Letters vol 109 Article ID 032001 2012
[12] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoSearchfor pair produced fourth-generation up-type quarks in ppcollisions atradic119904 = 7 TeV with a lepton in the final staterdquo PhysicsLetters B vol 718 pp 307ndash328 2012
[13] G Aad B Abbott J Abdallah et al ldquoSearch for pair and singleproduction of new heavy quarks that decay to a Z boson and athird-generation quark in pp collisions at radic119904 = 8TeV with theATLAS detectorrdquo Journal of High Energy Physics vol 2014 no11 article 104 2014
[14] G Aad T Abajyan B Abbott et al ldquoSearch for pair productionof heavy top-like quarks decaying to a high-pTW boson and ab quark in the lepton plus jets final state at radic119904 = 7TeV with theATLAS detectorrdquo Physics Letters B vol 718 no 4ndash5 pp 1284ndash1302 2013
[15] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoSearchfor heavy top-like quark pair production in the dilepton finalstate in pp collisions at radic119904 = 7TeVrdquo Physics Letters B vol 716no 1 pp 103ndash121 2012
[16] G Aad B Abbott J Abdallah et al ldquoSearch for heavy vector-like quarks coupling to light quarks in protonndashproton collisionsat radic119904 = 7 Tev with the ATLAS detectorrdquo Physics Letters B vol712 no 1-2 pp 22ndash39 2012
[17] G Aad T Abajyan B Abbott et al ldquoSearch for a heavy top-quark partner in final states with two leptons with the ATLASdetector at the LHCrdquo Journal of High Energy Physics vol 2012article 94 2012
[18] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoCom-bined search for the quarks of a sequential fourth generationrdquoPhysical Review D vol 86 no 11 Article ID 112003 20 pages2012
[19] R Ciftci ldquoAnomalous single production of the fourth gener-ation quarks at the CERN LHCrdquo Physical Review D vol 78Article ID 075018 2008
[20] I T Cakır H D Yıldız O Cakır and G Unel ldquoAnomalousresonant production of the fourth-family up-type quarks at theLHCrdquo Physical Review D vol 80 Article ID 095009 2009
[21] M Sahin S Sultansoy and S Turkoz ldquoSearching for the fourthfamily quarks through anomalous decaysrdquo Physical Review Dvol 82 no 5 Article ID 051503 2010
[22] M Bobrowski A Lenz J Riedl and J Rohrwild ldquoHow muchspace is left for a new family of fermionsrdquo Physical Review Dvol 79 no 11 Article ID 113006 15 pages 2009
[23] G Eilam B Melic and J Trampetic ldquo119862119875 violation and thefourth generationrdquo Physical Review D vol 80 no 11 Article ID116003 2009
[24] O Cobanoglu E Ozcan S Sultansoy and G Unel ldquoOPUCEMa library with error checkingmechanism for computing obliqueparametersrdquo Computer Physics Communications vol 182 no 8pp 1732ndash1743 2011
[25] T Han and J L Hewett ldquoTop-charm associated production inhigh energy 119890+119890minus collisionsrdquo Physical Review D vol 60 ArticleID 074015 1999
[26] A Belyaev N D Christensen and A Pukhov ldquoCalcHEP 34for collider physics within and beyond the standard modelrdquoComputer Physics Communications vol 184 no 7 pp 1729ndash1769 2013
[27] J Pumplin D Robert Stump J Huston H-L Lai P Nadolskyand W-K Tung ldquoNew generation of Parton distributions withuncertainties from global QCD analysisrdquo Journal of High EnergyPhysics vol 2002 article 012 2002
[28] G L Bayatian S Chatrchyan G Hmayakyan et al ldquoCMSphysics technical design report volume II physics perfor-mancerdquo Journal of Physics G Nuclear and Particle Physics vol34 no 6 p 995 2007
[29] T Sjostrand S Mrenna and P Skands ldquoPYTHIA 64 physicsand manualrdquo Journal of High Energy Physics vol 2006 no 5 p026 2006
[30] J Conway R Culbertson and R Demina Pretty Good Sim-ulation (PGS4) httpwwwphysicsucdavisedusimconwayresearchsoftwarepgspgs4-generalhtm
14 Advances in High Energy Physics
[31] EXROOTANALYSIS package for PGS4 data analysishttpmadgraphhepuiuceduDownloadsExRootAnalysis
[32] R Brun et al An object oriented data analysis framework(ROOT) httpsrootcernchdrupal
[33] F del Aguila and J A Aguilar-Saavedra ldquoMultilepton produc-tion via top flavour-changing neutral couplings at the CERNLHCrdquo Nuclear Physics B vol 576 pp 56ndash84 2000
[34] T Han M Hosch K Whisnant B-L Young and X ZhangldquoSingle top quark production via FCNC couplings at hadroncollidersrdquo Physical Review D vol 58 Article ID 073008 1998
[35] T Stelzer Z Sullivan and S Willenbrock ldquoSingle-top-quarkproduction at hadron collidersrdquoPhysical ReviewD vol 58 no 9Article ID 094021 11 pages 1998
Figure 16The contour plot of anomalous coupling andmass of newheavy quark 1198871015840 for the dynamical parametrization explained in thetext with a significance of 3120590 atradic119904 = 13TeV and 119871 int = 100fb
minus1
50 100 150 200 250 300 350 400
Entr
ies
0
2000
4000
6000
8000
10000
PhotonJet 1
pT (GeV)
Figure 17 Transverse momentum distributions of leading jet andphoton (119887120574 production) for signal after detector simulation
the signal is the high 119901119895119879andor 119901120574
119879and single 119887-tagged jet
We calculate the signal and background events in the range|119898
rec1198871015840 (GeV) minus 700GeV| lt 50GeV and we find a similar
significance as shown in Figure 16
5 Conclusion
The new heavy quarks of up-type and down-type can be pro-duced with large numbers at the LHC if they have the anoma-lous couplings (via flavor changing neutral current) thatwell dominate over the charged current interactions The
Entr
ies
50 100 150 200 250 300 350 4000
2000
4000
6000
8000
10000
12000
PhotonJet 1
pT (GeV)
Figure 18 Transverse momentum distributions of leading jet andphoton (119895120574 production) for background at the given conditionsmentioned in the text
500 550 600 650 700 750 800 850 900 950 10000
500
1000
1500
2000
2500
3000
BackgroundSignal
Mrecb998400
(GeV)
Even
ts10
GeV
Figure 19The reconstructedmass distributions for background andsignal (119887120574) with119898
1198871015840 = 700GeV and 120581Λ = 03TeVminus1
single production of new heavy quarks can be achievedthrough the anomalous interactions at the LHC with radic119904 =13TeV The anomalous vertices could appear significantly atleading order processes due to the possibility of new heavyquarks From the results of signal significance calculationsfor 1199051015840 (1198871015840) anomalous productions the sensitivity to theanomalous couplings 120581119905
1015840
Λ (1205811198871015840
Λ) can be reached down to010 TeVminus1 (015 TeVminus1) in the lepton + 119887jet + jet +MET (119887jet +jet) channel at radic119904 = 13TeV assuming a dynamical para-metrization for the anomalous couplings and the mass of 750GeV for the new heavy quarks The observability limits onthe anomalous couplings obtained after the simulation arecomparable with the partonic level analysis in the photon and119885 boson associated channels whereas the productions 119905119892 and119887119892 are less comparable due to the fast simulation method In
Advances in High Energy Physics 13
any case the single 119887 tagging will play an important role inprobing new heavy quarks and reducing the background
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgment
This work was supported in part by Turkish Atomic EnergyAuthority (TAEA) under Project Grant no 2011TAEKCERN-A5H2P101-19
References
[1] H J He N Polonsky and S F Su ldquoExtra families Higgs spec-trum and oblique correctionsrdquo Physical Review D vol 64 no5 Article ID 053004 11 pages 2001
[2] B Holdom W S Hou T Hurth M L Mangano S Sultansoyand G Unel ldquoFour statements about the fourth generationrdquoPMC Physics A vol 3 article 4 2009
[3] A Atre M Carena T Han and J Santiago ldquoHeavy quarksabove the top at the Tevatronrdquo Physical ReviewD vol 79 ArticleID 054018 2009
[4] A Atre G Azuelos M Carena et al ldquoModel-independentsearches for new quarks at the LHCrdquo Journal of High EnergyPhysics vol 2011 no 8 article 080 2011
[5] N Chen and H J He ldquoLHC signatures of two-Higgs-doubletswith fourth familyrdquo Journal of High Energy Physics vol 2012article 062 2012
[6] M S Chanowitz ldquoElectroweak constraints on the fourth gener-ation at two loop orderrdquo Physical Review D vol 88 Article ID015012 2013
[7] S Chakdar K Ghosh S Nandi and S K Rai ldquoCollider signa-tures of mirror fermions in the framework of a left-right mirrormodelrdquo Physical Review D vol 88 Article ID 095005 2013
[8] X F Wang C Du and H J He ldquoLHC Higgs signatures fromtopflavor seesaw mechanismrdquo Physics Letters B vol 723 no 4-5 pp 314ndash323 2013
[9] S Bar-Shalom M Geller S Nandi and A Soni ldquoTwo higgsdoublets a 4th generation and a 125GeV higgs a reviewrdquoAdvances in High Energy Physics vol 2013 Article ID 67297228 pages 2013
[10] H Fritzsch and D Holtmannspotter ldquoThe production of singlet-quarks at LEP and HERArdquo Physics Letters B vol 457 no 1ndash3pp 186ndash192 1999
[11] G Aad B Abbott J Abdallah et al ldquoSearch for down-typefourth generation quarks with the ATLAS detector in eventswith one lepton and hadronically decaying119882 bosonsrdquo PhysicalReview Letters vol 109 Article ID 032001 2012
[12] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoSearchfor pair produced fourth-generation up-type quarks in ppcollisions atradic119904 = 7 TeV with a lepton in the final staterdquo PhysicsLetters B vol 718 pp 307ndash328 2012
[13] G Aad B Abbott J Abdallah et al ldquoSearch for pair and singleproduction of new heavy quarks that decay to a Z boson and athird-generation quark in pp collisions at radic119904 = 8TeV with theATLAS detectorrdquo Journal of High Energy Physics vol 2014 no11 article 104 2014
[14] G Aad T Abajyan B Abbott et al ldquoSearch for pair productionof heavy top-like quarks decaying to a high-pTW boson and ab quark in the lepton plus jets final state at radic119904 = 7TeV with theATLAS detectorrdquo Physics Letters B vol 718 no 4ndash5 pp 1284ndash1302 2013
[15] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoSearchfor heavy top-like quark pair production in the dilepton finalstate in pp collisions at radic119904 = 7TeVrdquo Physics Letters B vol 716no 1 pp 103ndash121 2012
[16] G Aad B Abbott J Abdallah et al ldquoSearch for heavy vector-like quarks coupling to light quarks in protonndashproton collisionsat radic119904 = 7 Tev with the ATLAS detectorrdquo Physics Letters B vol712 no 1-2 pp 22ndash39 2012
[17] G Aad T Abajyan B Abbott et al ldquoSearch for a heavy top-quark partner in final states with two leptons with the ATLASdetector at the LHCrdquo Journal of High Energy Physics vol 2012article 94 2012
[18] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoCom-bined search for the quarks of a sequential fourth generationrdquoPhysical Review D vol 86 no 11 Article ID 112003 20 pages2012
[19] R Ciftci ldquoAnomalous single production of the fourth gener-ation quarks at the CERN LHCrdquo Physical Review D vol 78Article ID 075018 2008
[20] I T Cakır H D Yıldız O Cakır and G Unel ldquoAnomalousresonant production of the fourth-family up-type quarks at theLHCrdquo Physical Review D vol 80 Article ID 095009 2009
[21] M Sahin S Sultansoy and S Turkoz ldquoSearching for the fourthfamily quarks through anomalous decaysrdquo Physical Review Dvol 82 no 5 Article ID 051503 2010
[22] M Bobrowski A Lenz J Riedl and J Rohrwild ldquoHow muchspace is left for a new family of fermionsrdquo Physical Review Dvol 79 no 11 Article ID 113006 15 pages 2009
[23] G Eilam B Melic and J Trampetic ldquo119862119875 violation and thefourth generationrdquo Physical Review D vol 80 no 11 Article ID116003 2009
[24] O Cobanoglu E Ozcan S Sultansoy and G Unel ldquoOPUCEMa library with error checkingmechanism for computing obliqueparametersrdquo Computer Physics Communications vol 182 no 8pp 1732ndash1743 2011
[25] T Han and J L Hewett ldquoTop-charm associated production inhigh energy 119890+119890minus collisionsrdquo Physical Review D vol 60 ArticleID 074015 1999
[26] A Belyaev N D Christensen and A Pukhov ldquoCalcHEP 34for collider physics within and beyond the standard modelrdquoComputer Physics Communications vol 184 no 7 pp 1729ndash1769 2013
[27] J Pumplin D Robert Stump J Huston H-L Lai P Nadolskyand W-K Tung ldquoNew generation of Parton distributions withuncertainties from global QCD analysisrdquo Journal of High EnergyPhysics vol 2002 article 012 2002
[28] G L Bayatian S Chatrchyan G Hmayakyan et al ldquoCMSphysics technical design report volume II physics perfor-mancerdquo Journal of Physics G Nuclear and Particle Physics vol34 no 6 p 995 2007
[29] T Sjostrand S Mrenna and P Skands ldquoPYTHIA 64 physicsand manualrdquo Journal of High Energy Physics vol 2006 no 5 p026 2006
[30] J Conway R Culbertson and R Demina Pretty Good Sim-ulation (PGS4) httpwwwphysicsucdavisedusimconwayresearchsoftwarepgspgs4-generalhtm
14 Advances in High Energy Physics
[31] EXROOTANALYSIS package for PGS4 data analysishttpmadgraphhepuiuceduDownloadsExRootAnalysis
[32] R Brun et al An object oriented data analysis framework(ROOT) httpsrootcernchdrupal
[33] F del Aguila and J A Aguilar-Saavedra ldquoMultilepton produc-tion via top flavour-changing neutral couplings at the CERNLHCrdquo Nuclear Physics B vol 576 pp 56ndash84 2000
[34] T Han M Hosch K Whisnant B-L Young and X ZhangldquoSingle top quark production via FCNC couplings at hadroncollidersrdquo Physical Review D vol 58 Article ID 073008 1998
[35] T Stelzer Z Sullivan and S Willenbrock ldquoSingle-top-quarkproduction at hadron collidersrdquoPhysical ReviewD vol 58 no 9Article ID 094021 11 pages 1998
any case the single 119887 tagging will play an important role inprobing new heavy quarks and reducing the background
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgment
This work was supported in part by Turkish Atomic EnergyAuthority (TAEA) under Project Grant no 2011TAEKCERN-A5H2P101-19
References
[1] H J He N Polonsky and S F Su ldquoExtra families Higgs spec-trum and oblique correctionsrdquo Physical Review D vol 64 no5 Article ID 053004 11 pages 2001
[2] B Holdom W S Hou T Hurth M L Mangano S Sultansoyand G Unel ldquoFour statements about the fourth generationrdquoPMC Physics A vol 3 article 4 2009
[3] A Atre M Carena T Han and J Santiago ldquoHeavy quarksabove the top at the Tevatronrdquo Physical ReviewD vol 79 ArticleID 054018 2009
[4] A Atre G Azuelos M Carena et al ldquoModel-independentsearches for new quarks at the LHCrdquo Journal of High EnergyPhysics vol 2011 no 8 article 080 2011
[5] N Chen and H J He ldquoLHC signatures of two-Higgs-doubletswith fourth familyrdquo Journal of High Energy Physics vol 2012article 062 2012
[6] M S Chanowitz ldquoElectroweak constraints on the fourth gener-ation at two loop orderrdquo Physical Review D vol 88 Article ID015012 2013
[7] S Chakdar K Ghosh S Nandi and S K Rai ldquoCollider signa-tures of mirror fermions in the framework of a left-right mirrormodelrdquo Physical Review D vol 88 Article ID 095005 2013
[8] X F Wang C Du and H J He ldquoLHC Higgs signatures fromtopflavor seesaw mechanismrdquo Physics Letters B vol 723 no 4-5 pp 314ndash323 2013
[9] S Bar-Shalom M Geller S Nandi and A Soni ldquoTwo higgsdoublets a 4th generation and a 125GeV higgs a reviewrdquoAdvances in High Energy Physics vol 2013 Article ID 67297228 pages 2013
[10] H Fritzsch and D Holtmannspotter ldquoThe production of singlet-quarks at LEP and HERArdquo Physics Letters B vol 457 no 1ndash3pp 186ndash192 1999
[11] G Aad B Abbott J Abdallah et al ldquoSearch for down-typefourth generation quarks with the ATLAS detector in eventswith one lepton and hadronically decaying119882 bosonsrdquo PhysicalReview Letters vol 109 Article ID 032001 2012
[12] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoSearchfor pair produced fourth-generation up-type quarks in ppcollisions atradic119904 = 7 TeV with a lepton in the final staterdquo PhysicsLetters B vol 718 pp 307ndash328 2012
[13] G Aad B Abbott J Abdallah et al ldquoSearch for pair and singleproduction of new heavy quarks that decay to a Z boson and athird-generation quark in pp collisions at radic119904 = 8TeV with theATLAS detectorrdquo Journal of High Energy Physics vol 2014 no11 article 104 2014
[14] G Aad T Abajyan B Abbott et al ldquoSearch for pair productionof heavy top-like quarks decaying to a high-pTW boson and ab quark in the lepton plus jets final state at radic119904 = 7TeV with theATLAS detectorrdquo Physics Letters B vol 718 no 4ndash5 pp 1284ndash1302 2013
[15] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoSearchfor heavy top-like quark pair production in the dilepton finalstate in pp collisions at radic119904 = 7TeVrdquo Physics Letters B vol 716no 1 pp 103ndash121 2012
[16] G Aad B Abbott J Abdallah et al ldquoSearch for heavy vector-like quarks coupling to light quarks in protonndashproton collisionsat radic119904 = 7 Tev with the ATLAS detectorrdquo Physics Letters B vol712 no 1-2 pp 22ndash39 2012
[17] G Aad T Abajyan B Abbott et al ldquoSearch for a heavy top-quark partner in final states with two leptons with the ATLASdetector at the LHCrdquo Journal of High Energy Physics vol 2012article 94 2012
[18] S Chatrchyan V Khachatryan A M Sirunyan et al ldquoCom-bined search for the quarks of a sequential fourth generationrdquoPhysical Review D vol 86 no 11 Article ID 112003 20 pages2012
[19] R Ciftci ldquoAnomalous single production of the fourth gener-ation quarks at the CERN LHCrdquo Physical Review D vol 78Article ID 075018 2008
[20] I T Cakır H D Yıldız O Cakır and G Unel ldquoAnomalousresonant production of the fourth-family up-type quarks at theLHCrdquo Physical Review D vol 80 Article ID 095009 2009
[21] M Sahin S Sultansoy and S Turkoz ldquoSearching for the fourthfamily quarks through anomalous decaysrdquo Physical Review Dvol 82 no 5 Article ID 051503 2010
[22] M Bobrowski A Lenz J Riedl and J Rohrwild ldquoHow muchspace is left for a new family of fermionsrdquo Physical Review Dvol 79 no 11 Article ID 113006 15 pages 2009
[23] G Eilam B Melic and J Trampetic ldquo119862119875 violation and thefourth generationrdquo Physical Review D vol 80 no 11 Article ID116003 2009
[24] O Cobanoglu E Ozcan S Sultansoy and G Unel ldquoOPUCEMa library with error checkingmechanism for computing obliqueparametersrdquo Computer Physics Communications vol 182 no 8pp 1732ndash1743 2011
[25] T Han and J L Hewett ldquoTop-charm associated production inhigh energy 119890+119890minus collisionsrdquo Physical Review D vol 60 ArticleID 074015 1999
[26] A Belyaev N D Christensen and A Pukhov ldquoCalcHEP 34for collider physics within and beyond the standard modelrdquoComputer Physics Communications vol 184 no 7 pp 1729ndash1769 2013
[27] J Pumplin D Robert Stump J Huston H-L Lai P Nadolskyand W-K Tung ldquoNew generation of Parton distributions withuncertainties from global QCD analysisrdquo Journal of High EnergyPhysics vol 2002 article 012 2002
[28] G L Bayatian S Chatrchyan G Hmayakyan et al ldquoCMSphysics technical design report volume II physics perfor-mancerdquo Journal of Physics G Nuclear and Particle Physics vol34 no 6 p 995 2007
[29] T Sjostrand S Mrenna and P Skands ldquoPYTHIA 64 physicsand manualrdquo Journal of High Energy Physics vol 2006 no 5 p026 2006
[30] J Conway R Culbertson and R Demina Pretty Good Sim-ulation (PGS4) httpwwwphysicsucdavisedusimconwayresearchsoftwarepgspgs4-generalhtm
14 Advances in High Energy Physics
[31] EXROOTANALYSIS package for PGS4 data analysishttpmadgraphhepuiuceduDownloadsExRootAnalysis
[32] R Brun et al An object oriented data analysis framework(ROOT) httpsrootcernchdrupal
[33] F del Aguila and J A Aguilar-Saavedra ldquoMultilepton produc-tion via top flavour-changing neutral couplings at the CERNLHCrdquo Nuclear Physics B vol 576 pp 56ndash84 2000
[34] T Han M Hosch K Whisnant B-L Young and X ZhangldquoSingle top quark production via FCNC couplings at hadroncollidersrdquo Physical Review D vol 58 Article ID 073008 1998
[35] T Stelzer Z Sullivan and S Willenbrock ldquoSingle-top-quarkproduction at hadron collidersrdquoPhysical ReviewD vol 58 no 9Article ID 094021 11 pages 1998
[31] EXROOTANALYSIS package for PGS4 data analysishttpmadgraphhepuiuceduDownloadsExRootAnalysis
[32] R Brun et al An object oriented data analysis framework(ROOT) httpsrootcernchdrupal
[33] F del Aguila and J A Aguilar-Saavedra ldquoMultilepton produc-tion via top flavour-changing neutral couplings at the CERNLHCrdquo Nuclear Physics B vol 576 pp 56ndash84 2000
[34] T Han M Hosch K Whisnant B-L Young and X ZhangldquoSingle top quark production via FCNC couplings at hadroncollidersrdquo Physical Review D vol 58 Article ID 073008 1998
[35] T Stelzer Z Sullivan and S Willenbrock ldquoSingle-top-quarkproduction at hadron collidersrdquoPhysical ReviewD vol 58 no 9Article ID 094021 11 pages 1998
![KXUUø Ahep A6p ¤ù }Éh - Vikersund Utleiesenter · 2020. 3. 27. · KXUUø Ahep A6p ¤ù }Éh KXUU hp}Éh AühA¹ p} pAüÉhÁÉÉ""ùAh}]h 6üÉ}}Éh¤ 66p ÁÉh×}]h 6ü ¤ ¹°ü66üÉhÉ""Éh}]hh"](https://static.documents.pub/doc/80x56/60b970c6b410112e3e0590d2/kxuu-ahep-a6p-h-vikersund-utleiesenter-2020-3-27-kxuu-ahep-a6p.jpg)
