Olivier RavatLes Houches/June 3rd 20031 Higgs associated production at LHC : Thecase Olivier Ravat,...

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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

Transcript of Olivier RavatLes Houches/June 3rd 20031 Higgs associated production at LHC : Thecase Olivier Ravat,...

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

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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

MMHH = 120 GeV = 120 GeV

SStructure tructure functionfunction: CTEQ 5L: CTEQ 5L

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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Tuning Pythia parametersTuning Pythia parametersParameterParameter MeaningMeaning Default Default TuneTune

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