ICHEP ’04, Beijing, August 20, 2004
Eric Kajfasz, CPPM/D0 1
Search for Search for Extra-DimensionsExtra-Dimensions
at pp and ep Collidersat pp and ep Colliders
Eric Kajfasz, CPPM/[email protected]
for the CDF, D0, H1 and Zeus collaborations
__
ICHEP ’04, Beijing, August 20, 2004
Eric Kajfasz, CPPM/D0 2
Extra Dimensions: OutlineExtra Dimensions: Outline
• Extra Dimension Models and Signatures studied at CDF & D0 Run II, H1 and ZEUS
• Preliminary results on virtual graviton/gauge boson exchange and direct graviton emission
• Summary and Conclusions
• Why ED?o come “naturally” with string theoryo provide mechanism to explain why MEW <<
MPL
o ...
ICHEP ’04, Beijing, August 20, 2004
Eric Kajfasz, CPPM/D0 3
Extra Dimensions: Models Extra Dimensions: Models ExploredExplored
focus on n extra dims in models where SM fermions live on a D3-brane:• Large Extra Dimensions (LED) Arkani-Hamed,Dimopoulos,Dvali Phys Lett B429 (98)
o MPL ~ 1019GeVo n >= 2 compact and flat - MS : string/fundamental scale
M2PL ~ Rn MS
n+2 => MS can be lowered to TeV scaleo gravitons propagate in the bulk => Kaluza-Klein tower G(k)
o can’t resolve successive modes (0.01eV:n=2; 1MeV:n=3; 100MeV:n=6)=> expect:
• virtual exchange of graviton KK modes• real graviton emission
• TeV-1 Extra Dimension (TeV-1) Dienes,Dudas,Gherghetta Nucl Phys B537 (99)
o MC : compactification scale (~ TeV)o gauge fields can propagate in the bulk => KK towers of gauge bosonso modes with nearly equal energy spacing ~TeVo lower GUT scale by changing running of the couplings=> expect:
• resonances at high energies (LHC ...)• virtual exchange (Hera, Tevatron)
ICHEP ’04, Beijing, August 20, 2004
Eric Kajfasz, CPPM/D0 4
• Warped Extra Dimension (RS) Randull,Sundrum Phys Rev Lett 83 (99)
o ED of size R, highly curved, compactified on S1/Z2 orbifold: y = R.
o Zero mode graviton G(0) localized at the Planck-brane (y = 0) o SM fields localized on TeV-brane (y = R)o metric: ds2 = e-2kR dxdx – R2d2
k: curvature scalefor kR ~ 11-12, = MPLe-kR~ TeV
o consistency => 0.01 < k/MPL 0.1
o Gravitons propagate in the bulk => KK tower G(n) of modes of mass mn = xnke-kR (xn: 1st Bessel func. zeros i.e. 3.83, 7.02, 10.17, ...)=> well separated modes
= m1MPL/(kx1) => model characterized by m1 and k/MPL
o => Look for first graviton resonance
Extra Dimensions: Models Extra Dimensions: Models Explored ...Explored ...
yy=0 y=R
ICHEP ’04, Beijing, August 20, 2004
Eric Kajfasz, CPPM/D0 5
Extra Dimensions: Topologies Extra Dimensions: Topologies ExploredExplored
KK
q
q_
ee, ,
G
q
q_ g(jet),
jet(s) + MET+ MET
ExchangeVirtual Gravitons(LED,TeV-1,RS)
Emission ofReal Gravitons
(LED)
KKee
jetp
Tevatron
Tevatron
Hera
ICHEP ’04, Beijing, August 20, 2004
Eric Kajfasz, CPPM/D0 6
Large Extra DimensionsLarge Extra DimensionsVirtual Graviton ExchangeVirtual Graviton Exchange
G(n) G(n)
_/Z f
f
G(n) f
f
G(n) f
f
_ _
dilepton channel(Tevatron)
diphoton channel(Tevatron)
DIS channel(Hera)
G(n)
SM
SM
SM
ICHEP ’04, Beijing, August 20, 2004
Eric Kajfasz, CPPM/D0 7
Large Extra DimensionsLarge Extra DimensionsVirtual Graviton ExchangeVirtual Graviton Exchange
• Effect of ED parameterized by a single variable:
• different formalisms have different definitions of MS:o Hewett: (Hewett, Phys Rev Lett 82, 4765 (99) )
F = 2/ with = ± 1
o GRW: (Giudice, Rattazzi, Wells, hep-ph/9811291)
F = 1
o HLZ: (Han, Lykken, Zhang, hep-ph/9811350)
F = log(MS2/s) for n = 2
F = 2/(n-2) for n > 2
G= F/ MS4
= SM + Gint + G2KK
ICHEP ’04, Beijing, August 20, 2004
Eric Kajfasz, CPPM/D0 8
Large Extra Dimensions:Large Extra Dimensions: Virtual Graviton Exchange Virtual Graviton Exchange
• 2 isolated e’s, ET> 25 GeV
• e’s coming from luminous region• MET significance cut• CC = 92.4 ± 0.4% CP = 79.2 ± 0.5%
• for Mee > 350 GeV: Nexp = 4.6, Nobs = 8
• Mee distrib. used in binned likelihood => Limits on G=/MS
4
CC+CP
C(entral): ||<1 P(lug) : 1<||<3
Mee
95% CL limits on MS (TeV)
eeee
ICHEP ’04, Beijing, August 20, 2004
Eric Kajfasz, CPPM/D0 9
Large Extra Dimensions:Large Extra Dimensions: Virtual Graviton Exchange Virtual Graviton Exchange
• diEM = combine ee and o 2 EM objects, ET > 25 GeV
with track isolationo overall ID efficiency: 85 ± 1 %
• for MdiEM > 350 GeV:Nexp = 9.7 (1.6 QCD), Nobs = 8
• Systematics: ~ 12%
CC-CC + CC-EC
CC: ||<1.1 EC: 1.5<||<2.4
signal for G = 0.6
200pb-1
diEMdiEM
QCD D-Y+direct +QCDCC-CC + CC-EC
ICHEP ’04, Beijing, August 20, 2004
Eric Kajfasz, CPPM/D0 10
Large Extra Dimensions:Large Extra Dimensions: Virtual Graviton Exchange Virtual Graviton Exchange
Run II
Run I+II
• Data agree with SM predictions =>
• MdiEM vs|cos*| distrib. used
in 2D Binned Likelihood
• =>Set limits on G alone orin combination with Run I results
• => give 95% CL limits on MS (TeV)
• Most stringent constraints on LED for n > 2 to date among all experiments.
200pb-1
diEMdiEM
ICHEP ’04, Beijing, August 20, 2004
Eric Kajfasz, CPPM/D0 11
Large Extra Dimensions:Large Extra Dimensions: Virtual Graviton Exchange Virtual Graviton Exchange
250pb-1
• 2 ’s with PT > 15 GeVo isolated, ||<2.0o cosmic vetoo M > 50 GeV
• for M > 300 GeV:Nexp = 6.4 and Nobs = 5
• Systematics: ~ 13%D0 RunII Preliminary
Mvs|cos*| distr. used
in 2D Binned Likelihood=> Set limits on G
=> 95% CL limits on MS (TeV)
ICHEP ’04, Beijing, August 20, 2004
Eric Kajfasz, CPPM/D0 12
Large Extra Dimensions:HERALarge Extra Dimensions:HERA Virtual Graviton Exchange Virtual Graviton Exchange
G(k) Virtual exchange in t-channel interferes with Deep Inelastic Scattering (DIS)
Small contribution ~ O(1%) from eg -> eg G(k) exchange affects the Q2 distribution at high Q2
Compare d/dQ2 to what is expected from SM
Q2 = (k-k’)2 = -q2
,KK
ICHEP ’04, Beijing, August 20, 2004
Eric Kajfasz, CPPM/D0 13
Large Extra Dimensions:Large Extra Dimensions: Virtual Graviton Exchange Virtual Graviton Exchange
Hewett formalis
m
DISDIS
H1 s1/2(GeV) Lint(pb-1)
e+
p301 36
e+
p319 65
e- p 319 162 fit of d/dQ2
no deviation from SM=> Set limits on G
=> 95% CL limits on MS (TeV)
ICHEP ’04, Beijing, August 20, 2004
Eric Kajfasz, CPPM/D0 14
Large Extra Dimensions: Large Extra Dimensions: Virtual Graviton Exchange Virtual Graviton Exchange
Hewett formalism:
= - 1 : MS > 0.79 TeV = + 1 : MS > 0.78 TeV
DISDIS
Zeus s1/2(GeV) Lint(pb-1)
e+ p 301/319 112
e- p 319 16
d/dQ2 used in binned
likelihood=> Set limits on G
=> 95% CL limits on MS (TeV)
ICHEP ’04, Beijing, August 20, 2004
Eric Kajfasz, CPPM/D0 15
Large Extra Dimensions:Large Extra Dimensions:Direct Graviton EmissionDirect Graviton Emission
• Graviton produced along with a jet disappears in the bulk, undetected => mono-jet like topology with high MET
n = 6 and MS = 0.7 TeV
• Final Selection:o MET > 150 GeVo PT(jet1) > 150 GeV, || < 1o PT(jet2) < 50 GeV(MET,jet1) > 30o
• Nexp = 100.2 ± 6.3 (stat) ± 7.5 (theo) + 50 - 30 (JES)• Nobs = 63 (~ 5% efficiency)
QCD
MC SM bkg: mostlyZ->+jet(s)
85pb-1
MS
n
(K = 1)
updated analysis with 200pb-1
and new JES in process ...
limits on MS
~ 660-680 GeV
jet(s)+METjet(s)+MET
ICHEP ’04, Beijing, August 20, 2004
Eric Kajfasz, CPPM/D0 16
TeVTeV-1-1 Extra Dimension: Extra Dimension:Virtual Exchange of Z/Virtual Exchange of Z/ KK states KK states
• (> 1 EM w/ track match)
• same procedure as for LED analysis but with virtual Z/ KK states effects parameterized by:
C = 2/3MC2
• Nexp = 12.1 (4.3 QCD), Nobs = 9
• => Limit set as done for LED: C < 2.63 TeV-2 =>
MC > 1.12 TeV @ 95% CL
KK states modify the Z/ propagators:1/Q2 -> 1/Q2 + C
1/(Q2+MZ2) -> 1/(Q2+MZ
2) + C
Fit to e+p and e-p data =>
MC > 1.0 TeV @ 95% CL
D0: D0: eeee
H1: DISH1: DIS
200pb-1
signal for C = 5 TeV-2
from combined precision EW measurements: MC > 6.6 TeV
LEPLEP
QCD D-Y+ QCD
ICHEP ’04, Beijing, August 20, 2004
Eric Kajfasz, CPPM/D0 17
RS Extra DimensionRS Extra Dimension
• Graviton KK states well separated => resonant graviton search:
• CDF analyses:o ee and : binned likelihood methodo counting limits using 3 mass window around resonance
• D0 analysis:o diEM: using 3 mass window method
ICHEP ’04, Beijing, August 20, 2004
Eric Kajfasz, CPPM/D0 18
RS Extra DimensionRS Extra Dimension
ee
data agree with expected SM bkg ...
ee, ee, , ,
ee:• 2 isolated e’s w/ ET>25GeV• CC or CP
:• 2 isolated ’s w/ PT>20GeV• |1| <1, |2|<1.5• cosmic veto
:• 2 isolated ’s w/ ET>15GeV• CC
ICHEP ’04, Beijing, August 20, 2004
Eric Kajfasz, CPPM/D0 19
RS Extra DimensionRS Extra Dimension
ee
ee, ee, , ,
• cross-section limits computed from binned likelihood (ee,) and 3- mass window ()• compare to R-S cross-section for different values of the k/MPL parameter.
=> exclusion contour plot ...
ICHEP ’04, Beijing, August 20, 2004
Eric Kajfasz, CPPM/D0 20
RS Extra DimensionRS Extra Dimension
Lower limits on MG (GeV) for k/MPL = 0.1
ee
620 605 690
ee, ee, , ,
Further improvement can be achieved by:• using mass window method for dilepton channels• combining channels
ICHEP ’04, Beijing, August 20, 2004
Eric Kajfasz, CPPM/D0 21
RS Extra DimensionRS Extra Dimension
signal RS Graviton MG = 300 GeV
same diEM data set as for LED search
data agree with expected SM background => set limits with mass window method
diEMdiEM
200pb-1
785 GeV
QCDD-Y+direct + QCD
CC-CC + CC-EC
ICHEP ’04, Beijing, August 20, 2004
Eric Kajfasz, CPPM/D0 22
SummarySummary
LED = -1MS(TeV) >
= +1MS(TeV) >
CDF 0.99 0.96
D0diEM
1.10 1.22
D0/I+IIdiEM
1.16 1.28
D0
0.95 0.97
H1 0.78 0.82
ZEUS 0.79 0.78
RS MG(GeV) >@k/MPL=0.1
CDF
605
CDFee
620
CDF
690
D0ee
660
D0diEM
785
TeV-1 MC(TeV) >
D0 1.12
H1 1.0
LEP 6.6
n
MS
(K = 1)
ICHEP ’04, Beijing, August 20, 2004
Eric Kajfasz, CPPM/D0 23
ConclusionsConclusions
• Tevatron, CDF&D0 working well• CDF&D0 have by now each ~ 450pb-1 on tape• Tevatron and HERA are great tools to start looking for
ED’s• Very competitive results and even most stringent limits
are starting to come out• There is still room for improvement, so stay tuned. • However, for the final word on some models, we may
very well need to wait for LHC ...