Higgs Boson Production - CBPF

Main.dviHiggs Boson
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√ 2Gµ)
2 = 2 √ 2Gµ M2
√ 2Gµ M2
H × (i)
The Higgs boson couplings to fermions and gauge bosons and the Higgs self–couplings in the SM. The normalization factors of the Feynman rules are also displayed. – from: A. Djouadi, arXiv:hep-ph/0503172v2
• Higgs boson interactions
ious L terms developed pre-
viously
CQ’s book
• More advanced, A.Djouadi
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HHZ Htt
He+eHZH ps = 500 GeV(e+e ! HX) [fb MH [GeV 500300200160130100
100 10
1 0.1
ttHZHWHHqq gg ! H mt = 178 GeVMRST/NLOps = 14 TeV(pp! H +X) [pb
MH [GeV 1000100 100
Lepton (e+e−) Collider Hadron (pp) Collider
On Lepton Colliders, very clean events but: e+e− → H is hoplessly small
µ+µ− is scaled by (mµ/me)2 ∼ 40.000 (muon cooling under study)
e+e− → ZH (“higgs-strahlung”) was the search mode at LEP
A.Djouadi
hep-ph/050317
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SppS Tevatron LHC
SLD LEP KEK PEP-II
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1.0
0.1
gg→H
Phys.Lett.B273,167(1991)
(pb)
roughly compares with inclusive tt production;
(light H); σm=125GeV ∼ 0.7pb σ tt
∼ 7pb
highest, and provides a lepton signature “signature”
example of
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[GeV] HM 100 200 300 400 500 1000
H +
X )
→pp
→pp
→ pp
→ pp
increasingly relevant:
• gg → ttH (heavy-q fusion)
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– a brand-new generation of detectors...
Arthur Maciel, C. Jordao, SP (Jan. 2013) 6
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• Higgs boson decay rates are calculated in CQ sec. 6.5.
Exercise: reproduce the Γ(H → ff) calculation
• Three important (tree-level) examples are:
Γ(H → ff) = Nc × GFm
W /M2 H)
Γ(H → ZZ) = GFM
Z/M 2 H)
• “Branching Ratios” are next plotted as a function of MH
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H ig
gs B
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[GeV]HM 100 120 140 160 180 200
H ig
gs B
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H ig
gs B
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H ig
gs B
– production by gluon fusion
– very small yields,
– but extremely pure,
– practically no bkgnds
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H ig
gs B
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A likely candidate for
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1
10
155 160 165 170 175 180 185 190 195 200
1
10
mH(GeV/c2)
95 %
Expected
Observed
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1
10
100 110 120 130 140 150 160 170 180 190 200
1
10
mH(GeV/c2)
95 %
Expected Observed ±1σ Expected ±2σ Expected
LEP Exclusion Tevatron Exclusion
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1
10
100 110 120 130 140 150 160 170 180 190 200
1
10
M Tevatron Run II Preliminary, L ≤ 10.0 fb -1
Observed Expected w/o Higgs ±1 s.d. Expected ±2 s.d. Expected LE
P E
xc lu
si on
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[GeV]HM 100 120 140 160 180 200
H ig
gs B
– production by gluon fusion
– very small yields,
– but extremely pure,
– practically no bkgnds
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(for a mass near 125 GeV)
• ∼500 events delivered (10fb−1)
• Final state:
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76K scintillating Xtals (PbWO4)
• (7 → 8) TeV:
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classes according to MVA
(S/B)-weighted
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E ve
nt s
/ G eV
4th order polynomial
Selected diphoton sample
ATLAS Preliminary
[GeV]γγm
D at
S M
σ/σ 95
PreliminaryATLAS
γγ→SM H -1L dt = 4.8 fb∫= 7 TeV, sData 2011, -1L dt = 5.9 fb∫= 8 TeV, sData 2012,
[GeV]Hm
S ig
) < 6.0 H
,mµ(λ-2 ln
PreliminaryATLAS -1Ldt = 4.8 fb∫ = 7 TeV: s -1Ldt = 5.9 fb∫ = 8 TeV: s
γγ→SM H
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E ve
nt s
/ 2 G
Selected diphoton sample
H Sig+Bkg Fit (m Bkg (4th order polynomial)
[GeV]γγm 100 110 120 130 140 150 160
E ve
nt s-
F it
S M
σ/σ 9
5% C
L lim
it on
[GeV]Hm
110 115 120 125 130 135 140 145 150 0
Lo ca
= 7 TeVsData 2011 -1
-1 Ldt = 13.0 fb∫
• local significance: 6.1 σ
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Four lepton final states ( = e, µ)
• The “golden channel”
σ×BR ∼ 2 fb
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E ve
nt s
/ 3 G
E ve
nt s
/ 3 G
12 Data
Z+X
,ZZ*γZ
=126 GeVHm
CMS Preliminary -1 = 8 TeV, L = 5.26 fbs ; -1 = 7 TeV, L = 5.05 fbs
4e, 4µ
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E ve
nt s
/ 3 G
12 Data
Z+X
,ZZ*γZ
=126 GeVHm
4e, 4µ
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E ve
nt s
/ 1 0
G eV
E ve
nt s
/ 1 0
G eV
25 Data
Z+X
,ZZ*γZ
[GeV]4lm 110 120 130 140 150 160 170 180
E ve
nt s
/ 3 G
eV 0
8 Data
Z+X
,ZZ*γZ
=126 GeVHm
backgrounds well described for all 4 masses observed significance
at 125.5 GeV: 3.2σ
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E ve
nt s/
5 G
4l→(*) ZZ→H
Data (*)Background ZZ
H Signal (m
=150 GeV) H
E ve
nt s/
5 G
4l→(*) ZZ→H
H Signal (m
=150 GeV) H
E ve
nt s/
5 G
eV
0
5
10
15
20
25
30
35
-1Ldt = 4.8 fb∫ = 7 TeV: s -1Ldt = 5.8 fb∫ = 8 TeV: s
4l→(*) ZZ→H
H Signal (m
=150 GeV) H
[GeV]Hm 110 120 130 140 150 160 170 180
S M
σ/σ 95
210 PreliminaryATLAS
4l→(*) ZZ→H -1Ldt =4.8 fb∫=7 TeV, s -1Ldt =5.8 fb∫=8 TeV, s
sCLObserved
sCLExpected
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E ve
nt s/
10 G
eV
0
5
10
15
20
25
30
35
40
-1Ldt = 4.8 fb∫ = 7 TeV: s -1Ldt = 5.8 fb∫ = 8 TeV: s
4l→(*) ZZ→H
H Signal (m
=190 GeV) H
)µ S
ig na
Best Fit ) < 1µ(λ-2 ln
Best Fit ) < 1µ(λ-2 ln
PreliminaryATLAS -1Ldt = 4.8 fb∫ = 7 TeV: s -1Ldt = 5.8 fb∫ = 8 TeV: s
• observed excess data near 125 GEV
with local significance of 3.4σ
(SM expected 2.6σ)
nal region, a∼30% excess of ZZ backgnds
at high mass under investigation
• fitted signal strength (σ×BR/SM)
at 125 GeV: µ = 1.3± 0.6
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Characterization
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CMS combined γγ ⊕ Z(∗)Z
Higgs boson mass (GeV) 116 118 120 122 124 126 128 130
Lo ca
γγ →H
ZZ→H
CMS Preliminary γγ ZZ + →H
-1 = 7 TeV, L = 5.1 fbs -1 = 8 TeV, L = 5.3 fbs
Higgs boson mass (GeV) 116 118 120 122 124 126 128 130
Lo ca
= 7 TeVs
= 8 TeVs
CMS Preliminary γγ ZZ + →H
-1 = 7 TeV, L = 5.1 fbs -1 = 8 TeV, L = 5.3 fbs
the two high sensitivity and high mass resolution channels
channel γγ Z(∗)Z comb. expected
signif. 4.1 3.2 5.0 4.7
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[GeV]Hm 100 200 300 400 500 600
S M
σ/σ 95
ATLAS Preliminary 2011 + 2012 Data
CLs Limits
[GeV]Hm 110 115 120 125 130 135 140 145 150
S M
σ/σ 95
ATLAS Preliminary 2011 + 2012 Data
CLs Limits
0 Lo
-1Ldt = 4.6-4.8 fb∫ = 7 TeV: s
ATLAS Preliminary
2011 + 2012 Data
[GeV]Hm 110 115 120 125 130 135 140 145 150
0 Lo
-1Ldt = 4.6-4.8 fb∫ = 7 TeV: s
ATLAS Preliminary
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[GeV]Hm 115 120 125 130 135
0p
-1310
-1110
-910
-710
-510
-310
-110
10
310
510
σ0σ1 σ2 σ3
Combined
bb→W,Z H
-1Ldt = 4.6 - 4.8 fb∫ = 7 TeV: s -1Ldt = 13 fb∫ = 8 TeV: s
-1Ldt = 4.6 fb∫ = 7 TeV: s -1Ldt = 13 fb∫ = 8 TeV: s
-1Ldt = 13 fb∫ = 8 TeV: s
= 126.5 GeVHm
mu for mh at 126.5 GeV for the individual chan-
nels and their combination.
experiment to be more signal-like than the ob-
servation as a function of mh. The dashed curve
shows the median expected local p0 under the
hypothesis of a production of a Standard Model
Higgs boson with that mass.
ATLAS-CONF-2012-170
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in the associated production (V + bb) channels
• Compatible with the LHC discovery observations
• Compatible with the
SM Higgs hypothesis
SMσ/σBest Fit 0 1 2 3 4 5 6 7
b b→H
June 2012
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SMσ/σBest fit 0 0.5 1 1.5 2 2.5
ZZ→H
WW→H
γγ →H
ττ →H
bb→H
-1 12.2 fb≤ = 8 TeV, L s -1 5.1 fb≤ = 7 TeV, L s
CMS Preliminary = 125.8 GeVH m
)µSignal strength ( -1 0 +1
Combined
bb→W,Z H
-1Ldt = 4.6 - 4.8 fb∫ = 7 TeV: s -1Ldt = 13 fb∫ = 8 TeV: s
-1Ldt = 13 fb∫ = 8 TeV: s
= 125 GeVHm
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What does this mean?
• Indicates a vacuum condensate that gives masses to bosons and fermions
• Preserves unitarity in reactions with longitudinal gauge bosons (WL and ZL)
• Leaves us with the hierarchy + fine tuning problem (indicative of PBSM)
– protection via symmetry (SUSY) – OK to all energies
– protection via (large or warped) extra dimensions
– protection via Higgs compositeness
∗ where the light Higgs is analogous to the pion
∗ partial protection – something else must happen at higher energies
from A.
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Conclusion
• Major indicator of a new general direction in HEP
• EWSB observables have become manifestly available
• Theory and experiment need to adapt themselves
• This is the beginning of a new era in HEP...

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Higgs Boson Production - CBPF