Transcript Higgs Vector Boson Fusion Production and Detection at the

Higgs Vector Boson Fusion
Production and Detection at the
Tevatron
Rick St. Denis – Glasgow University
Outline
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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
q
q
nm
q'
W+
W+
m+
0
H
WW-
q'
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Missing Et
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High Pt Leptons
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ne
e-
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2 forward jets, opposite in
rapidity, high mass
Spin 0 Higgs correlates
spins of leptons: e,m
parallel and neutrinos also
Dhe-jet about 1-1.5
Kraemer vs Pythia
Comparison of Pythia to Kraemer
0.94
0.92
Kraemer/Pythia
0.90
whlnubbbar
0.88
zhnunubbbar
0.86
zhllbbbar
0.84
0.82
0.80
0
50
100
150
Higgs Mass (GeV/c2)
200
250
Production:Check Pythia, Kraemer,
Spira
Below 1
Kraemer Variation in Correction to Pythia LO for WH
1.20
(NLO+EW)/LO
1.00
0.80
0.60
0.40
0.20
0.00
100
110
120
130
140
150
160
170
2
Higgs Mass (GeV/c )
180
190
200
ZH corrections
Kraemer Variation in Correction to Pythia LO for ZH
2.50
(NLO+EW)/LO
2.00
1.50
1.00
0.50
0.00
100
110
120
130
140
150
160
Higgs Mass (GeV/c2)
170
180
190
200
Interesting Diversion: pp vs ppbar
Ratio of  (ppbar-H->X)/ (pp->H->X) at 1960 GeV
5.00
4.50
4.00
(ppbar)/ (pp)
3.50
ZH
wh-lnubbbar
3.00
zh-nunubbbar
WH
2.50
2.00
1.50
gg-H-ww
wh-www
VBF
vbf
1.00
0.50
zh llbbbar
gg
0.00
100 110 120 130 140 150 160 170 180 190 200
Higgs Mass (GeV/c2)
VBF 25% Better in PbarP
d
u
d
u
W+
W-
d u
d u
WHence:
ppbar:
u,d
u,d
pp:
W+
u
d
UUD
UUD
UUD
5 chances
UUD
4 chances
Ratio is
5/4 = 1.25
Check of Higgs Branching Ratios
Higgs Branching Ratios
1.000
0.900
0.800
Branching Ratio
0.700
B
WW
ccbar
0.600
bbbar
tautau
0.500
gg
zz
0.400
ZZ
0.300
0.200
0.100
0.000
100 110 120 130 140 150 160 170 180 190 200
2
Higgs Mass (GeV/c )
ww
Check of Higgs BR: Pythia/Spira
Pythia/Spira BR
1.30
20-25% differences
1.20
Pythia/Spira BR
1.10
BB
TAU
1.00
CC
GG
0.90
WW
ZZ
0.80
0.70
0.60
100 110 120 130 140 150 160 170 180 190 200
2
Higgs Mass (GeV/c )
Apply NLO to Pythia
WH(lnbb)
Higgs Events ( xBr) per fb (NNLO,100% Acceptance,
Perfect Detector)
Used WW
correction
For VBF
100.0
Total
ZH(nnbb)
zh-nunubbbar
zh llbbbar
Events
ZH(llbb)
wh-lnubbbar
10.0
gg-H-ww
wh-www
vbf
1.0
10
0
11
0
12
0
13
0
14
0
15
0
16
0
17
0
18
0
19
0
20
0
gg-WW
Total
WH-WWW
VBF
0.1
2
Higgs Mass (GeV/c )
For
-1
8fb
-1
Higgs Events ( x Br) 8fb (NNLO, 100% Acceptance,
Perfect Detector)
1000
Higgs Events
wh-lnubbbar
100
zh-nunubbbar
zh llbbbar
gg-H-ww
wh-www
vbf
10
Total
1
100 110 120 130 140 150 160 170 180 190 200
Higgs Mass (GeV/c2)
Study Characteristics at 130, 160,
200
q
q'
^s
q
nm
q'
W+
W+
m+
0
H
WW-
ne
e-
Tev, MH=160
Pt, Rapidity of Leptons, Jets
Reasonably
Triggerable
Quark
Forward
Pt Quark can
be low
Electron
In CDF
Tev, MH=160
Rapidity of two quarks
Min h
of 2
quarks
Dh
of 2
quarks
Max h
of 2
quarks
Tev, MH=160
Missing Energy
60 GeV
Met
Met vs
Pte
Met 180o from e
Quark can
be along
Met
Tev, MH=160
Lepton Correlations:e-ne
Df (e,ne)
e,neanticorrelated in f
Tev, MH=160
Lepton Correlations: e-m
e,m correlated
in y,phi and
have high pt
DR
Masses
Large Invariant
Mass between
leptons
High Invariant
Mass between
quarks
Tev, MH=160
Mt for e m n
Tev, MH=160
Electron-Jet Separation
Mh=130
2
GeV/c ,
Tevatron
Tev, MH=130
Pt, Rapidity of Leptons, Jets
Less
Triggerable
Quark
Forward,
like 160
Pt Quark can
be low
Electron
In CDF
Tev, MH=130
Rapidity of two quarks
Min h
of 2
quarks
Dh
of 2
quarks
Max h
of 2
quarks
Missing Energy Tev, MH=130
Less Missing Et, slightly lower pt leptons
Met , q less correlated
Met , e less correlated
Tev, MH=130
Lepton Correlations:e-ne
Df (e,ne)
e,ne less anticorrelated in f
Tev, MH=130
Lepton Correlations
e,m not as
correlated
DR
Masses
Slightly less
Invariant
Mass between
leptons
Less Invariant
Mass between
quarks
Tev, MH=130
Mt for e m n
Tev, MH=130
Electron-Jet Separation
Same
Separation
Mh=200
2
GeV/c ,
Tevatron
Tev, MH=200
Pt, Rapidity of Leptons, Jets
More
Triggerable
Quark still
Forward,
not much
change
Pt Quark can
be low
Electron
In CDF
Tev, MH=200
Rapidity of two quarks
Max h
of 2
quarks
Min h
of 2
quarks
Not Much
Change
Dh
of 2
quarks
Missing Energy
Tev, MH=200
Higher Missing Et, Higher pt leptons
Met , q same
Met , e stronger corr.
Tev, MH=200
Lepton Correlations
e,m much less
correlated
Tev, MH=200
Lepton Correlations:e-ne
Df (e,ne)
e,ne more anticorrelated, in f
but not at 180o
Larger Invariant
Mass between
leptons
Masses
Larger Invariant
Mass between
quarks
Tev, MH=200
Mt for e m n
Tev, MH=200
Electron-Jet Separation
Same l-j
separation
Mh=160
2
GeV/c ,
LHC
LHC, MH=160
Pt, Rapidity of Leptons, Jets
Reasonably
Triggerable
Quark more
Forward
Pt Quark can
be low
Electron
In CDF:
wider distn
At LHC
LHC, MH=160
Rapidity of two quarks
Min h
–
wider
Dh
of 2
Quarks
wider
Max h
of 2
Quarks
wider
LHC, MH=160
Missing Energy
A bit larger at LHC
LHC, MH=160
Lepton Correlations:e-ne
Df (e,ne)
e,ne anticorrelated less sharply in
f
LHC, MH=160
Lepton Correlations
e,m better
correlated
Masses
Larger Invariant
Mass between
leptons
Higher Invariant
Mass between
quarks
LHC, MH=160
Mt for e m n
LHC, MH=160
Electron-Jet Separation
Same l-j
separation
Conclusions
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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 m
signal correlation
Large missing Energy, Lepton correlations due
to spin, Invariant mass of tagging jets good
handles.
Conclusions (cont)
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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
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Check Cross section for VBF properly
Check correlations in MET, e, m, jet for help in
mass reco/ efficiency
Study backgrounds for same distributions
Develop estimators: avoid hard cuts in order to
conserve events
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Move on to real simluations
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Study W to jet possibility, Higgs to t
Spare Slides
Kinematics
q
q'
^s
q
q'
W+
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nm
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W+
m+
0
H
WW-
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ne
e-
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^s : The local CM - pay
for this with PDF
MW Can keep ^ssmall
with W off shell
MH Can also reduce ^s
with H off shell
Can emit ISR to give pt to
H, but costs PDF
Vector Boson fusion Production
nm
q'
q
W+
W+
Wq
q'
m+
H0
W-
ene
Tev, MH=160
Missing Et Correlations
Tev, MH=160
Neutrinos
Tev, MH=160
Neutrinos