Post on 31-Dec-2015
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Higgs Vector Boson Fusion Production and Detection at the
Tevatron
Rick St. Denis – Glasgow University
Outline
● Vector Boson Fusion Production of Higgs● Production cross sections and
comparisons to current Tevatron favorite channels
● Event characteristics at MH=130, 160, 200 GeV/c2
● Comparison to LHC
VBF Production Features
● Missing Et● High Pt Leptons● 2 forward jets,
opposite in rapidity, high mass
● Spin 0 Higgs correlates spins of leptons: e,parallel and neutrinos also
● e-jet about 1-1.5
qq'
q
W+
W-
q'
H0
W+
W-
e-e-
+
e
Kraemer vs PythiaComparison of Pythia to Kraemer
0.80
0.82
0.84
0.86
0.88
0.90
0.92
0.94
0 50 100 150 200 250
Higgs Mass (GeV/c2)
Kra
em
er/
Py
thia
whlnubbbar
zhnunubbbar
zhllbbbar
Production:Check Pythia, Kraemer, Spira
Kraemer Variation in Correction to Pythia LO for WH
0.00
0.20
0.40
0.60
0.80
1.00
1.20
100 110 120 130 140 150 160 170 180 190 200
Higgs Mass (GeV/c2)
(NL
O+
EW
)/L
O
Below 1
ZH correctionsKraemer Variation in Correction to Pythia LO for ZH
0.00
0.50
1.00
1.50
2.00
2.50
100 110 120 130 140 150 160 170 180 190 200
Higgs Mass (GeV/c2)
(NL
O+
EW
)/L
O
Interesting Diversion: pp vs ppbar
Ratio of (ppbar-H->X)/(pp->H->X) at 1960 GeV
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
5.00
100 110 120 130 140 150 160 170 180 190 200
Higgs Mass (GeV/c2)
(p
pb
ar)
/ (
pp
) wh-lnubbbar
zh-nunubbbar
zh llbbbar
gg-H-ww
wh-www
vbf
W
gg
VBF
VBF 25% Better in PbarP
u d
W+
d
d u
W-
d u
W+
u
W-
pp:u
d
ppbar:u,d
u,d
Hence: U U D
U U D
U U D
U U D5 chances 4 chances
Ratio is5/4 = 1.25
Check of Higgs Branching Ratios
Higgs Branching Ratios
0.000
0.100
0.200
0.300
0.400
0.500
0.600
0.700
0.800
0.900
1.000
100 110 120 130 140 150 160 170 180 190 200
Higgs Mass (GeV/c2)
Bra
nc
hin
g R
ati
o ccbar
bbbar
tautau
gg
zz
ww
B
WW
ZZ
Check of Higgs BR: Pythia/SpiraPythia/Spira BR
0.60
0.70
0.80
0.90
1.00
1.10
1.20
1.30
100 110 120 130 140 150 160 170 180 190 200
Higgs Mass (GeV/c2)
Py
thia
/Sp
ira
BR
BB
TAU
CC
GG
WW
ZZ
20-25% differences
Apply NLO to PythiaHiggs Events (xBr) per fb (NNLO,100% Acceptance,
Perfect Detector)
0.1
1.0
10.0
100.0
100
110
120
130
140
150
160
170
180
190
200
Higgs Mass (GeV/c2)
Ev
en
ts
wh-lnubbbar
zh-nunubbbar
zh llbbbar
gg-H-ww
wh-www
vbf
Total
Total
WH(lbb)
WH-WWWVBF
gg-WW
ZH(llbb)
ZH(bb)
Used WW correctionFor VBF
For 8fb-1
Higgs Events ( x Br) 8fb-1 (NNLO, 100% Acceptance, Perfect Detector)
1
10
100
1000
100 110 120 130 140 150 160 170 180 190 200
Higgs Mass (GeV/c2)
Hig
gs
Eve
nts
wh-lnubbbar
zh-nunubbbar
zh llbbbar
gg-H-ww
wh-www
vbf
Total
Study Characteristics at 130, 160, 200
s
qq'
q
W+
W-
q'
H0
W+
W-
e-e-
+
e
Pt, Rapidity of Leptons, Jets
Quark Forward
Pt Quark canbe low
ElectronIn CDF
Reasonably Triggerable
Tev, H=160
Rapidity of two quarks
Min of 2 quarks
Max of 2 quarks
of 2 quarks
Tev, H=160
Missing EnergyTev, H=160
60 GeVMet
Met vs Pte
Quark can be alongMet
Met 180o from e
Lepton Correlations:e-e
Tev, H=160
e,eanticorrelated in
(e,e)
Lepton Correlations: e-
e,correlatedin y,phi andhave high pt
Tev, H=160
R
Masses
High Invariant Mass between quarks
Large Invariant Mass between leptons
Mt for e
Tev, H=160
Electron-Jet SeparationTev, H=160
Mh=130 GeV/c2, Tevatron
Pt, Rapidity of Leptons, Jets
Quark Forward, like 160
Pt Quark canbe low
ElectronIn CDF
Less Triggerable
Tev, H=130
Rapidity of two quarks
Min of 2 quarks
Max of 2 quarks
of 2 quarks
Tev, H=130
Missing EnergyLess Missing Et, slightly lower pt leptons
Tev, H=130
Met , e less correlatedMet , q less correlated
Lepton Correlations:e-e
Tev, H=130
e,e less anticorrelated in
(e,e)
Lepton Correlations
e,not as correlated
Tev, H=130
R
Masses
Less Invariant Mass between quarks
Slightly less Invariant Mass between leptons
Mt for e
Tev, H=130
Electron-Jet SeparationTev, H=130
Same Separation
Mh=200 GeV/c2, Tevatron
Pt, Rapidity of Leptons, Jets
Quark stillForward, not muchchange
Pt Quark canbe low
ElectronIn CDF
MoreTriggerable
Tev, H=200
Rapidity of two quarks
Min of 2 quarks
Max of 2 quarks
of 2 quarks
Tev, H=200
Not MuchChange
Missing EnergyHigher Missing Et, Higher pt leptons
Tev, H=200
Met , q same Met , e stronger corr.
Lepton Correlations
e,much less correlated
Tev, H=200
Lepton Correlations:e-e
Tev, H=200
e,e more anticorrelated, in but not at 180o
(e,e)
Masses
Larger Invariant Mass between quarks
Mt for e
Tev, H=200Larger Invariant Mass between leptons
Electron-Jet SeparationTev, H=200
Same l-j separation
Mh=160 GeV/c2, LHC
Pt, Rapidity of Leptons, Jets
Quark moreForward
Pt Quark canbe low
ElectronIn CDF: wider distnAt LHC
Reasonably Triggerable
LHC, H=160
Rapidity of two quarks
Min –wider
Max of 2 Quarkswider
of 2 Quarkswider
LHC, H=160
Missing Energy
A bit larger at LHC
LHC, H=160
Lepton Correlations:e-e
LHC, H=160
e,e anticorrelated less sharply in
(e,e)
Lepton Correlations
e,better correlated
LHC, H=160
Masses
Higher Invariant Mass between quarks
Larger Invariant Mass between leptons
Mt for e
LHC, H=160
Electron-Jet SeparationLHC, H=160
Same l-j separation
Conclusions● Cross sections and widths disagree at
20% level● NLO variation with scale can be large● Yield of VBF about 10% of gg->WW can
enhance after cuts● MET, Et and rapidity coverage for CDF
electrons fine, muons may need tricks using e signal correlation
● Large missing Energy, Lepton correlations due to spin, Invariant mass of tagging jets good handles.
Conclusions (cont)
● Best at 160, suffers some e-mu decorrelation and lower pt for lower masses, emu decorrelation but higher pt at higher mass.
● Detection in this mode relies on spin of Higgs: if you find it, how much have you also measured that it is spin 0?
Next Steps
● Check Cross section for VBF properly● Check correlations in MET, e, , jet for
help in mass reco/ efficiency● Study backgrounds for same distributions● Develop estimators: avoid hard cuts in
order to conserve events● Move on to real simluations● Study W to jet possibility, Higgs to
Spare Slides
Kinematics s● : The local CM - pay for this with PDF
● MW Can keep small with W off shell
● MH Can also reduce with H off shell
● Can emit ISR to give pt
to H, but costs PDF
s
ss
qq'
q
W+
W-
q'
H0
W+
W-
e-e-
+
e
Vector Boson fusion Production
qq'
q
W+
W-
q'
H0
W+
W-
e-e-
+
e
Missing Et CorrelationsTev, H=160
NeutrinosTev, H=160
NeutrinosTev, H=160