LHC Prospects on LHC Prospects on Standard Model Higgs Standard Model Higgs Riccardo Ranieri INFN and Università degli Studi di Firenze INFN and Università degli Studi di Firenze on behalf of ATLAS and CMS Collaborations on behalf of ATLAS and CMS Collaborations ICHEP’04 ICHEP’04 32 32 nd nd International Conference on High International Conference on High Energy Physics Energy Physics Beijing, China 16-22 August 2004 Beijing, China 16-22 August 2004
LHC Prospects on Standard Model Higgs. Riccardo Ranieri INFN and Università degli Studi di Firenze on behalf of ATLAS and CMS Collaborations ICHEP’04 32 nd International Conference on High Energy Physics Beijing, China 16-22 August 2004. ATLAS & CMS at LHC. - PowerPoint PPT Presentation
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LHC Prospects on LHC Prospects on Standard Model HiggsStandard Model Higgs
Riccardo Ranieri
INFN and Università degli Studi di FirenzeINFN and Università degli Studi di Firenze
on behalf of ATLAS and CMS Collaborationson behalf of ATLAS and CMS Collaborations
ICHEP’04ICHEP’04
3232ndnd International Conference on High Energy International Conference on High Energy PhysicsPhysics
Beijing, China 16-22 August 2004Beijing, China 16-22 August 2004
ICHEP’04Beijing, 16-22 August 2004
LHC Prospects on Standard Model Higgs
Riccardo Ranieri 2
ATLAS & CMS at LHCATLAS & CMS at LHC– Detectors optimised for Higgs boson
and SUSY searches very high energy: LHCLHC pp √s=14 TeVpp √s=14 TeV
hadronic jets in forward-backward regions– the forward jet tagging is a powerful
background rejection tool hadronic activity suppressed in low low ηη region
– emitted vector bosons are colour-singlets Search for →→ℓℓννℓ’ℓ’νν’’, , ℓℓνν+jet+jet final states
– S/√B≥5S/√B≥5 in mmHH=120=120÷÷140 GeV/c140 GeV/c22 range with 40 40 fbfb-1-1
» S/√B≈2.5S/√B≈2.5 in one LHC year in one LHC year» this process offers the possibility for a direct
measurement of Yukawa coupling H
Phys. Rev. D59(1999) 014037
ATL-PHYS-2003-004
CMS NOTE 2003/033
Jet
Higgs Decay products
Forward tagging jets
[VBF]
ICHEP’04Beijing, 16-22 August 2004
LHC Prospects on Standard Model Higgs
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Light Higgs SummaryLight Higgs Summary
Detector/performance requirements:Detector/performance requirements: HH→→ response uniformityresponse uniformity of electromagnetic
calorimeter HH→→bbbb b-taggingb-tagging capability of tracking system qqH(qqH(→→)) efficient jet reconstructionjet reconstruction in 3<|η|<5 aallll good understandingunderstanding (<10%) of the
backgroundbackground
Three complementary channelsThree complementary channels
Each channel contributes with ~22σσ to the total significance
Observation of all channels is very important to extract a Observation of all channels is very important to extract a convincing signal in the first year(s)convincing signal in the first year(s)
--
ICHEP’04Beijing, 16-22 August 2004
LHC Prospects on Standard Model Higgs
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High Mass Higgs: HHigh Mass Higgs: H→→WWWW(*)(*)
• VBF qqH→qqWW– Di-lepton final state
WW→ℓνℓν (ℓ=e,μ) b-jet and veto in the central
region to reject tt background
Drell-Yan background ee, μμ discarded with lepton cuts:
– Mℓℓ<75 GeV/c2; pTmiss>30
GeV/c
– Main decay channel around mH=170 GeV/c2
Isolated leptons WW(*)→ℓνℓν (ℓ=e,μ)Missing transverse energy ET
miss
Dangerous background from top decays
– central jet vetoWW spin correlations for the signal
– small ℓ+ℓ- opening angles
CMS NOTE 2003/033 ATL-PHYS-2003-005
10 fb-1 are more than enough if mH is around 170 GeV/c2
-
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LHC Prospects on Standard Model Higgs
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– The “goldengolden” channel well defined peaks ZZ→→μμ++μμ--
– mmHH>2m>2mZZ: real Z’s
main backgrounds– reducible: tt, Zbb
» μ isolation
» Z reconstruction (mZ)
– irreducible: ZZ» qq production mechanism
dominates softer muons Luminosity required for a 55σσ
discovery:– 1010-30 fb-30 fb-1-1 if m if mHH>2m>2mZZ
» 2-3 LHC years
– up to 100 fbup to 100 fb-1-1 if m if mHH<2m<2mZZ
» only one reconstructed Z» high luminosity runs
High mass Higgs: High mass Higgs: HH→→ZZZZ(*)(*)→→44μμ