Olivier Ravat Olivier Ravat Les Houches/June 3rd 2003 Les Houches/June 3rd 2003 1 Higgs Higgs associated production associated production at at L L H H C : C : l WH The The case case Olivier Ravat Olivier Ravat , Morgan Lethuillier , Morgan Lethuillier IPN Lyon IPN Lyon Les Houches 2003 : Physics at TeV Les Houches 2003 : Physics at TeV Colliders Colliders
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Olivier RavatLes Houches/June 3rd 20031 Higgs associated production at LHC : Thecase Olivier Ravat, Morgan Lethuillier IPN Lyon Les Houches 2003 : Physics.
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Olivier RavatOlivier Ravat Les Houches/June 3rd Les Houches/June 3rd 20032003
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HiggsHiggs associated production associated production at at LLHHC :C :
lWHTheThe casecase
Olivier RavatOlivier Ravat, Morgan Lethuillier, Morgan LethuillierIPN LyonIPN Lyon
Les Houches 2003 : Physics at TeV Colliders Les Houches 2003 : Physics at TeV Colliders
Olivier RavatOlivier Ravat Les Houches/June 3rd Les Houches/June 3rd 20032003
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Production at Production at LLHHCCSmall NLO Small NLO Corrections:Corrections:According to V2HV According to V2HV (M.Spira) a K factor (M.Spira) a K factor of 1.3 can be of 1.3 can be applied.applied.
NLONLOLOLO
MHMH
σ σ (pb)(pb)
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The pp The pp lνγγlνγγ channelchannel
SignalSignal
Signature :Signature : 2 2 hard photonshard photons reconstructing to the Higgs massreconstructing to the Higgs mass
1 1 charged leptoncharged lepton andand missing Pmissing PTT
Processes Processes with such a with such a final state :final state :
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This channel is far cleaner than the usual This channel is far cleaner than the usual H H γγγγ..
Less dependant on calorimeter Less dependant on calorimeter resolution.resolution.
Vertex reconstruction is easy, thanks to the Vertex reconstruction is easy, thanks to the charged lepton better measurement of Mcharged lepton better measurement of MHH
Increases theIncreases the coverage of MSSM coverage of MSSM(M(MAA,tg,tgββ) ) parameter space (D.Denegri, R.Kinnunen CMS-parameter space (D.Denegri, R.Kinnunen CMS-NOTE 96-091); interesting for the 2HDM(I). NOTE 96-091); interesting for the 2HDM(I).
History : A study has been performed in 1997 History : A study has been performed in 1997 at the generator level (M.Dubinin et Al. CMS at the generator level (M.Dubinin et Al. CMS NOTE 1997/101) and we would like to update the NOTE 1997/101) and we would like to update the study with a detector simulation.study with a detector simulation.
Motivations Motivations
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Generation of the physics eventsGeneration of the physics events
Signal generatedSignal generated withwith Pythia 6.2Pythia 6.2 andand CompHEP 41.10CompHEP 41.10 in order to perform in order to perform some cross-checks,some cross-checks,
Backgrounds generated with Backgrounds generated with CompHEP 41.10 CompHEP 41.10
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Cross-sections of signal and irreducible backgroundCross-sections of signal and irreducible background
Total NLO cross-section for WH production : 2 Total NLO cross-section for WH production : 2 pbpbIn order to assure an efficient production we In order to assure an efficient production we imposed some generator level cuts :imposed some generator level cuts :CutsCuts
ppTTγγ11 > 20 GeV> 20 GeV
PPT T γγ 22 > 20 GeV> 20 GeV
ppTTll >20 GeV>20 GeV
ΔΔR(R(γγ,l),l) >0.3>0.3
||ηη((γγ,l)|,l)| <2.7<2.7
σσ(pp (pp γ γγ γllυυ) .10) .1055 pb pb
SignalSignal 35.9635.96
BackgroundBackground 1174.51174.5
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Kinematics for the signal, Pythia and CompHEPKinematics for the signal, Pythia and CompHEP
PythiaPythiaCompHEPCompHEP
PythiaPythiaCompHEPCompHEP
PythiaPythiaCompHEPCompHEP
PythiaPythiaCompHEPCompHEP
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Kinematics for the signal, Pythia and CompHEPKinematics for the signal, Pythia and CompHEP
PythiaPythiaCompHEPCompHEP
PythiaPythiaCompHEPCompHEP
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From CompHEP 4-vectors to a simulated final stateFrom CompHEP 4-vectors to a simulated final state
Using Using cpyth_for_CMSIMcpyth_for_CMSIM (A. Sherstnev) : (A. Sherstnev) : hadronization and fragmentation with Pythia. hadronization and fragmentation with Pythia.
Output : HEPEVT ntuple compatible with Output : HEPEVT ntuple compatible with CMSJET and CMSIM. CMSJET and CMSIM.
Pythia tuned to fit the underlying event and Pythia tuned to fit the underlying event and the minimum bias using the CDF data, then the minimum bias using the CDF data, then extrapolation to LHC energies.extrapolation to LHC energies.
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MSTP(81)MSTP(81) Multiple parton interaction : onMultiple parton interaction : on 11 11
MSTP(82)MSTP(82) Varying impact parameter; hadronic matter Varying impact parameter; hadronic matter overlap consistent with a double gaussian overlap consistent with a double gaussian
distribution, with a smooth turn-off=PARP(82)distribution, with a smooth turn-off=PARP(82)
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PARP(82)PARP(82) 1.9 GeV1.9 GeV 2.0 GeV2.0 GeV
PARP(83)PARP(83) Double Gaussian : fraction of hadronic matter Double Gaussian : fraction of hadronic matter within PARP(84)within PARP(84)
0.50.5 0.50.5
PARP(84)PARP(84) Double Gaussian : fraction of the overall Double Gaussian : fraction of the overall hadron radius containing the fraction hadron radius containing the fraction
PARP(83) of the total hadronic matter.PARP(83) of the total hadronic matter.
0.20.2 0.40.4
PARP(85)PARP(85) Probability that the MPI produces 2 gluons Probability that the MPI produces 2 gluons with color connections to the nearest with color connections to the nearest
neighbour.neighbour.
0.330.33 0.90.9
PARP(86)PARP(86) Probability that the MPI produces 2 gluons Probability that the MPI produces 2 gluons either as in PARP(85) or as a closed gluon either as in PARP(85) or as a closed gluon
loop.loop.
0.660.66 0.950.95
PARP(89)PARP(89) Reference energy EReference energy E00 1 TeV1 TeV 1.8 TeV1.8 TeV
PARP(90)PARP(90) Determines the energy dependance of the cut-Determines the energy dependance of the cut-off Poff PT0 T0 as follows : Pas follows : PT0T0(E(ECUTCUT)=P)=PT0T0(E(ECMCM/E/E00))εε with with
E=PARP(90)E=PARP(90)
0.160.16 0.250.25
PARP(67)PARP(67) Scale factor that determines the maximum Scale factor that determines the maximum parton virtuality for space-like showers.parton virtuality for space-like showers.
1 1 44
(Rick Field settings)(Rick Field settings)
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CMSJET parametersCMSJET parameters
Noise in the ECAL barrel :Noise in the ECAL barrel :
Noise in the ECAL endcaps: Noise in the ECAL endcaps:
0.5% of dead cells.0.5% of dead cells.
30 MeV30 MeV30 MeV30 MeV
0.5%0.5%
150 MeV150 MeV150 MeV150 MeV
ppTT cut for photons : cut for photons :
20 GeV20 GeV20 GeV20 GeV
20 GeV20 GeV20 GeV20 GeV
ppTT cut for electron : cut for electron :
ppTT cut for muon : cut for muon : 10 GeV10 GeV10 GeV10 GeV
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CMSJET parametersCMSJET parameters
No charged particle with in a cone ΔR =0.3 around leptons and photons.
No cluster with more than in the calorimeters around leptons and photons.
Number of selected eventsNumber of selected events for 1 year at for 1 year at HL:HL:
5 GeV5 GeV5 GeV5 GeV
ppTT>2 GeV>2 GeVppTT>2 GeV>2 GeV
Signal : 14Signal : 14Background : Background :
214214
Signal : 14Signal : 14Background : Background :
214214
ΔΔR =0.3R =0.3ΔΔR =0.3R =0.3
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Results with ~17.3 events/bunch crossingResults with ~17.3 events/bunch crossing
CMS : 100 fb-1CMS : 100 fb-1
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Results with ~17.3 events/bunch crossingResults with ~17.3 events/bunch crossing
CutCut CutCutbs
bs
CMS : 100 fb-1CMS : 100 fb-1
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Results with ~17.3 events/bunch Results with ~17.3 events/bunch crossingcrossing
Nice, but does not yet include reducible Nice, but does not yet include reducible background…background…
After one year at high After one year at high luminosity, cuts of 55 luminosity, cuts of 55 GeV on the hard photon GeV on the hard photon and 30 GeV on the soft and 30 GeV on the soft one :one :
In a mass window In a mass window of 118.6<Mof 118.6<Mγγγγ<121.4 <121.4 we get we get 99.8
bs 99.8bs
CMS : 100 fb-1
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Conclusions and perspectivesConclusions and perspectives
The WHThe WH lνγγ lνγγ channel can hardly be channel can hardly be considered as a discovery channel but considered as a discovery channel but it’s very clean (almost free from it’s very clean (almost free from background!)background!)
It also allows a more precise It also allows a more precise measurement of Mmeasurement of MHH : the charged lepton : the charged lepton kills the pointing contribution on kills the pointing contribution on ΔΔMMHH;;
It would be a “rescue channel” in case of It would be a “rescue channel” in case of maximal stop mixing.maximal stop mixing.
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What’s next?What’s next?
The processing of 4-vectors with The processing of 4-vectors with CMSIM is on its way in view of full CMSIM is on its way in view of full simulation and reconstruction with simulation and reconstruction with ORCA.ORCA.
The generation of the ZH and ttH The generation of the ZH and ttH cases is performed both for signal cases is performed both for signal and background (analysis still to be and background (analysis still to be done).done).
Reducible backgrounds are being Reducible backgrounds are being produced produced