Searches for the Standard ModelSearches for the Standard ModelHiggs boson at LHCHiggs boson at LHC

A. Nikitenko, IC, London. On leave from ITEP, MoscowA. Nikitenko, IC, London. On leave from ITEP, Moscow

ICHEP2006, EW session, July 28, 2006ICHEP2006, EW session, July 28, 2006

CERN, Building 40

CMS ATLAS

Emphasize will be given to the new CMS PTDR results obtained at L=2x1033cm-2s-1

http://cmsdoc.cern.ch/cms/cpt/tdr/

CERN/LHCC 2006-001 CERN/LHCC 2006-021

Published printed in July 2006

LHC : 27 km long100m underground

General Purpose,pp, heavy ions

General Purpose,pp, heavy ions

CMS+TOTEM

ATLAS

Heavy ions, pp

ALICE

pp, B-Physics,CP Violation

The CMS Detector The CMS Detector today at point 5today at point 5

The ATLAS The ATLAS Barrel Toroid.Barrel Toroid.End of November 2005End of November 2005

SM Higgs mass constraints from the data and theorySM Higgs mass constraints from the data and theory

Indirect constraints from precision EW data : MH < 260 GeV at 95 %CL (2004) MH < 186 GeV with Run-I/II prelim. (2005) MH < 166 GeV (2006)

ExperimentExperiment SM theorySM theory

The triviality (upper) bound andvacuum stability (lower) bound asfunction of the cut-off scale “triviality” : Higgs self-coupling remains finite Direct limit from LEP: MH > 114.4 GeV

NLO

SM Higgs boson couplings and Br. ratiosSM Higgs boson couplings and Br. ratios

v is vev of Higgs field = 246 GeV

Right bottom plot includes uncertainties fromthe quark masses mt, mb, mc and s(MZ)

tree level couplingsDjouadi, Kalinowski, Spira

• Discovery of the inclusive Higgs boson Discovery of the inclusive Higgs boson production with decay modes:production with decay modes:– H->ZZ->4lH->ZZ->4l– H->H->– H->WW->2lH->WW->2l

H->ZZH->ZZ(*)(*)->4->4ll - golden mode - golden mode (first studies in CMS in 1995)(first studies in CMS in 1995)

Background: tt, ZZ, Background: tt, ZZ, llllbb (“Zbb”)bb (“Zbb”)

Selections :Selections :- lepton isolation in tracker and calolepton isolation in tracker and calo- lepton impact parameter, lepton impact parameter, , ee vertex , ee vertex - mass windows Mmass windows MZ(*)Z(*), M, MHH

H->ZZ->ee

H->ZZ->4lH->ZZ->4l

• New elements of analysis:

– ZZ background: NLO k factor depends on m4l

– background from side bands or from ZZ/Z; (gg->ZZ is

added as 20% of LO qq->ZZ, no good generator yet)

Signal and background at 5 sigma discoverySignal and background at 5 sigma discovery

ee ee

CMSCMSat 5at 5 sign. sign.

CMSCMSat 5at 5 sign. sign.

H->ZZ->4lH->ZZ->4l

Signal significance: new vs old results; no big changeSignal significance: new vs old results; no big change

~ 125 GeV~ 125 GeV

CP property with H->ZZ->4lCP property with H->ZZ->4l

d d ( () ~ H + ) ~ H + I + I + 22 A, A,H scalar, A – pseudoscalar,H scalar, A – pseudoscalar,=tan(=tan(), ), = +/- = +/- /2 --> A/2 --> A

C2 = Br / SM Br SM

CC22 needed to exclude SM h needed to exclude SM h

CMS CMS

Inclusive H->

CMS plot of the ECAL TDR time : December 1997CMS plot of the ECAL TDR time : December 1997

Went then from hybrid silicon + gas chamber trackerWent then from hybrid silicon + gas chamber tracker to all silicon tracker to all silicon tracker

CMSCMS CMSCMS

Discovery potential of H->

SMSM

light h->light h-> in MSSM in MSSMinclusive searchinclusive search

CMS CMS ECAL TDRECAL TDR

CMS PTDRCMS PTDR ATLASATLAS

NLONLO

count. expcount. exp

NLONLO

cut basedcut based

NLONLO

optimized*optimized*

TDR (LO)TDR (LO) New, NLONew, NLO

Cut basedCut based

New, NLONew, NLO

likelihoodlikelihood

~ 7.5~ 7.5 6.06.0 8.28.2 3.93.9 6.36.3 8.78.7

Significance for SM Higgs MSignificance for SM Higgs MHH=130 GeV for 30 fb=130 GeV for 30 fb-1-1

* NN with kinematics and * NN with kinematics and isolation as input, s/b per event isolation as input, s/b per event

Discovery of SM H->Discovery of SM H-> in associated ttH and WH in associated ttH and WH

production at high luminosityproduction at high luminosity Discovery of Wh, h->Discovery of Wh, h->Discovery of tth, h->Discovery of tth, h->

Significance of tth, h->Significance of tth, h->for 100 fbfor 100 fb-1-1

L=1034 cm-2 s-1

L=1034 cm-2 s-1

CMS

CMS

Accuracy of the Higgs boson mass Accuracy of the Higgs boson mass measurement with H->ZZ->4l and H->measurement with H->ZZ->4l and H->

Stat. error onlyStat. error only

Early discovery with H->WW->2l2Early discovery with H->WW->2l2

• New elements of analysisNew elements of analysis– PPTT Higgs and WW bkg. as at Higgs and WW bkg. as at

NLO (re-weighted in PYTHIA)NLO (re-weighted in PYTHIA)– include box gg->WW bkg.include box gg->WW bkg.– NLO Wt cross section after jet NLO Wt cross section after jet

veto veto • Backgrounds from the data Backgrounds from the data

(and theory)(and theory)– tt from the data; uncertainty tt from the data; uncertainty

16% at 5 fb16% at 5 fb-1-1

– WW from the data; uncertainty WW from the data; uncertainty 17% at 5 fb17% at 5 fb-1-1

– Wt and gg->WW bkg from theor. Wt and gg->WW bkg from theor. uncertainty 22% and 30% uncertainty 22% and 30%

after cuts: - ET

miss > 50 GeV - jet veto in < 2.4 - 30 <pT

l max<55 GeV - pT l min > 25 GeV - 12 < mll < 40 GeV

Discovery reach with H->WW->2lDiscovery reach with H->WW->2l

Excluded cross section timesBranching Ratio at 95% C.L. CMS Phys. TDR 2006CMS Phys. TDR 2006

very similar to old results w/o syst.

Luminosity needed for 5 Luminosity needed for 5 discovery discoveryfor incl. Higgs boson production for incl. Higgs boson production

Discovery of qqH associated Discovery of qqH associated production (Weak Boson Fusion)production (Weak Boson Fusion)

qq->qqHqq->qqH

(written in 2005)

Jet veto (“rapidity gap”) in VBF (WW->H) productionfirst discussed in :Yu. Dokshitzer, V. Khoze and S. Troyan, Sov.J.Nucl. Phys. 46 (1987) 712Yu. Dokshitzer, V. Khoze and T. Sjostrand, Phys.Lett., B274 (1992) 116

From D. Zeppenfeld; talk on TeV4LHC, 2004

First, full simulation analysis ofFirst, full simulation analysis ofqqH, H->qqH, H->->l+jet ->l+jet

Discovery in Standard ModelDiscovery in Standard Model

discoverydiscoveryof light hof light h in MSSM in MSSM

CMSCMSSMSM

Summary of SM Higgs boson discovery: Summary of SM Higgs boson discovery:

Signal Significance for 30 fbSignal Significance for 30 fb-1-1

with K factors

ATLAS h->ATLAS h-> sensitivity is now comparable with CMS sensitivity is now comparable with CMSCMS ttH, H->bb does not have even 3 CMS ttH, H->bb does not have even 3 with 60 fb with 60 fb-1-1

ATL-PHYS-PUB-2003/030

Measurement of the SM Higgs boson couplingsMeasurement of the SM Higgs boson couplings

ConclusionsConclusions• The latest simulation studies show: The latest simulation studies show:

– Inclusive h->2Inclusive h->2 could be discovered with < 10fb could be discovered with < 10fb-1-1

– almost no change in the discovery potential with almost no change in the discovery potential with H->ZZ->4l and H->WW->2l. H->ZZ->4l and H->WW->2l. – tth, h->bb is lost as CMS discovery channel even with tth, h->bb is lost as CMS discovery channel even with

60 fb60 fb-1-1

– qqh, h->qqh, h-> “survived” after full simulation ! The “survived” after full simulation ! The biggest discovery reach in Mbiggest discovery reach in MAA-tan -tan

– Mass measurement 0.1-1.0 % precisionMass measurement 0.1-1.0 % precision– Width measurement 10-5 % precision, MWidth measurement 10-5 % precision, MHH > 200 GeV > 200 GeV– CP with H->ZZCP with H->ZZ– Ratio of couplings: ~ 5-30 % Ratio of couplings: ~ 5-30 %

BACKUP

discrepancy from the SM for light h

M. Duhrssen et al.,hep-ph/0407190

Can MSSM be distinguished from SM in the area of only light Higgs discovery ?

Total weight 12500 tOverall diameter 15 mOverall length 21.6 m

Physics runs 2008-2009Physics runs 2008-2009

First , we should First , we should “discover” Standard Model“discover” Standard Model

~ 10~ 107-87-8 Z->ll, W->l Z->ll, W->l on tape during on tape during physics run in 2008-09 (~ 10fbphysics run in 2008-09 (~ 10fb-1 -1 ?)?)

Z, W, tt cross sections and expectedZ, W, tt cross sections and expectednumber of events after trigger in CMSnumber of events after trigger in CMS with 10 fbwith 10 fb-1-1

W/Z+nJ+X NLOpredictions at LHCwith cuts :

pTl > 15 GeV

|l| < 2.4 pT

j > 20 GeV |j| < 4.5 Rlj > 0.4 Rll > 0.2

W/Z bb + X |b| < 2.5

J. Campbell, R.K. Ellis, D. Rainwaterhep-ph/0308195

~ 106 tt->+X with 10 fb-1

W/Z+nJets is very important background for Higgs at LHC

topologytopology Background for Higgs channel (one example)Background for Higgs channel (one example)

W+1j+XW+1j+X gg->h->WW*->2l gg->h->WW*->2l W+2j+XW+2j+X MSSM gg->bbH, H->MSSM gg->bbH, H->->->ll+jet (one b-tag)+jet (one b-tag)W+3j+XW+3j+X VBF qq->qqh, h->VBF qq->qqh, h->->->ll+jet + 2 tag. jets+jet + 2 tag. jetsW+4j+XW+4j+X VBF qq->qqh, h->WW->VBF qq->qqh, h->WW->lljj + 2 tag jetsjj + 2 tag jetsZ+1j+XZ+1j+X MSSM gg->bbH, H->MSSM gg->bbH, H->->l+jet (one b-tag)->l+jet (one b-tag)Z+2j+XZ+2j+X VBF qq->qqh, h->VBF qq->qqh, h->->->ll+jet + 2 tag jets+jet + 2 tag jetsZ+4j+XZ+4j+X VBF qq->qqh, h->ZZ->VBF qq->qqh, h->ZZ->lllljj + 2 tag jetsjj + 2 tag jets

Zbb,Zcc, Wbb, Wcc (W/Z+QQ+nj) are as important as W/Z+njZbb,Zcc, Wbb, Wcc (W/Z+QQ+nj) are as important as W/Z+nj

• Discovery potential for the Higgs boson(s) Discovery potential for the Higgs boson(s) in CMS is updated in comparison with in CMS is updated in comparison with

Higgs Summary Note, CMS Note 2003 :Higgs Summary Note, CMS Note 2003 :– Latest trigger tableLatest trigger table– Bkg estimates from “data” and exp. Bkg estimates from “data” and exp.

systematicssystematics– Advanced generators for multi-jet events: Advanced generators for multi-jet events:

ALPGEN, MadGraph, CompHEP, TopRexALPGEN, MadGraph, CompHEP, TopRex– almost all analyses use full G4 simulation data almost all analyses use full G4 simulation data

New elements of PTDR 2006 analysis:New elements of PTDR 2006 analysis: - splitting into categories depending of R- splitting into categories depending of R99=E(3x3)/E=E(3x3)/Escsc and and regions regions

- usage of LLR for discovery, systematic- usage of LLR for discovery, systematic - - “optimized analysis” – NN with kinematics and “optimized analysis” – NN with kinematics and isolation as input, isolation as input, s/b per events/b per event

barrel with large Rbarrel with large R99 barrel with small Rbarrel with small R99

endcaps with large Rendcaps with large R99 endcaps with small Rendcaps with small R99

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