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Andrey Korytov, University of Florida SUSY’08, 16 June 2008, Seoul 1 Higgs Search at LHC (and LHC/CMS status) Andrey Korytov (for ATLAS and CMS Collaborations) proton beam proton beam M UO N CHAM BERS BARREL & ENDCAP SILICO N TRACKER FORW ARD C ALO RIM ETER TO TAL W EIG HT 12,500 ton O VERALL DIAM ETER 15 m O VERALL LENG TH 22 m SUPERCONDUCTING SO LEN O ID RETURN YOKE ELECTROMAGNETIC C A LO R IM ETER HADRON C A LO R IM ETER proton beam proton beam S

Higgs Search at LHC (and LHC/CMS status)

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Higgs Search at LHC (and LHC/CMS status). Andrey Korytov (for ATLAS and CMS Collaborations). ATLAS CMS. Outline. LHC status CMS Experiment status Standard Model Higgs boson MSSM Higgs bosons. - PowerPoint PPT Presentation

Text of Higgs Search at LHC (and LHC/CMS status)

  • Higgs Search at LHC(and LHC/CMS status)Andrey Korytov

    (for ATLAS and CMS Collaborations)ATLAS CMS

  • OutlineLHC status

    CMS Experiment status

    Standard Model Higgs bosonMSSM Higgs bosons

  • LHC status and plans

  • LHC statusLHC sectors are being cooled downthe last sector 45 will be at ~2K in July

    Some magnets needadditional training to reach Bmax

    To have the beam this year,LHC will start out at 10 TeV(no additional training needed)

    Magnets will be re-trained duringwinter shutdown to allow forthe 2009 run at 14 TeV

    T~2K, ready for cold tests, commissioning, and beam

  • LHC plan for 2008-20092008beam commissioning Aug-Octcenter-of-mass energy 10 TeV (some magnets need further training)peak luminosity 51031 cm-2s-1physics run 40 days (Oct-Nov)overall efficiency* 0.1 (based on the 1st year of LEP1)integrated luminosity 20 pb-1 (delivered for physics)

    2009center-of-mass energy 14 TeVpeak luminosity 1033 cm-2s-1physics run 150 days (May-Nov)overall efficiency* 0.2 (based on subsequent years of LEP1)integrated luminosity 2.5 fb-1 (delivered for physics)

  • CMS commissioning status

  • CMS experiment statusMuon SystemSolenoidHadron CalorimetersEM CalorimeterTracker

  • CMS MagnetParameters:superconducting4 Tesladiameter 6 mlength 13 mstored energy 2.6 GJ64 Bar Radial Pressure

    Status:fully tested while still on surfacecold and ready to be energized initial field will be 3.8 T

  • CMS Tracker Parameters:coverage |h|
  • EM Calorimeter Parameters:barrel + endcaps: |h|
  • CMS Hadron Calorimeter Parameters:barrel/endcap |h|
  • CMS Muon System Parameters:coverage |h|
  • Cosmic Muon Events in CMSAugust 2006on the surface, B=3.8 T(not all detectors on)May 2008underground, B=0 TECALHCAL

  • Cosmic Ray Muons on surfaceMagnet Test and Cosmic Challenge in 2006-07Magnet reliably operates at 3.8 TFraction of all sub-detectors were operationalMany million cosmic ray events were collectedCosmic ray muons were successfully reconstructed, including their momenta, charge ratio, etc.

  • Cosmic Ray Muons undergroundphotograph: one of the endcapmuon system stations occupancy plot: muon hits registered in that station

  • Higgs search prospectsMore details are in parallel session talks:SM Higgs boson with ATLAS (Francesco Polci)SM Higgs boson H 2g with CMS (Serguei Ganjour)SM Higgs boson H ZZ(*) and WW(*) with CMS (Sinjini Sen Gupta)SM Higgs boson produced in VBF with ATLAS (Guilherme Hanninger) SM Higgs boson produced in VBF with CMS (Pietro Govoni)SM Higgs boson in associated production mode with ATLAS (Huaqiao Zhang)MSSM Neutral Higgs bosons with ATLAS (Jana Schaarschmidt )MSSM Neutral Higgs A/H 2m and 2t with CMS (Georgios Anagnostou)MSSM Charged Higgs bosons with ATLAS (Christopher Potter)

  • SM Higgs: what we know from theoryOne pseudo-scalar doublet F (4 degrees of freedom) Potential V = l|F|4 - m2|F|2

    After spontaneous symmetry breaking: W and Z acquire masses (3 degrees of freedom) the last remaining degree of freedom (4-3=1): scalar CP-even Higgs of unknown massl runs with Q: small mH at 1-TeV scale at some Q, l(Q) < 0 V has no minimum (vacuum breaks loose) large mH at 1-TeV scale at some Q, l(Q) = theory is non-perturbative (theorists retire) chimney l(Q) ~ const due to cancellation of +/- terms (fine tuning)

    mass must be within 50-600 TeV range

  • What we know experimentally: LEPDirect search at LEP:mH>114.4 GeV @ 95%CL

  • What we know experimentally: EWK fitsEWK precision data:mH
  • What we know experimentally: TevatronNote for the range around mH~160 GeV:

    The fact the currently observed limit runs ahead of the expected limit (left plot) makes it less likely to observe a 3s-excess later (right plot does not include these effects)

  • SM Higgs at LHCColored cells = { detailed studies available }YES = { discovery in the appropriate range of masses at L
  • Forerunners: analyses to see the Higgs firstATLAS is coming up with many major updates nowK factors included2006

    mass~120~140~160190-600ATLASVBF, Httincl., HggVBF, HWW*VBF, HWWincl., HZZCMSincl., Hggincl., HZZ*incl., HWW

  • SM Higgs: Hgg Backgrounds:prompt ggprompt g + jet(brem g, p0g)dijets

    CMS-2006 analysis:cut-basedevents sorted by em shower qualitykinematics, isolation, Mgg-peak optimizedloose sorting and kinematical cutsevent-by-event kinematical Likelihood Ratio with bkgd pdf taken from sidebands, signal pdf from MCsystematic errors folded inCMS 2006ATLAS 2006S=6 @ L=30agree

    mH=130 GeVCMSNLO cut based (TDR-2006)6.0 sNLO neural net (TDR-2006)8.2 sATLASLO cut based (TDR-1999)3.9 sNLO cut based (2006, stat. err. only)6.3 sNLO likelihood (2006, stat. err. only)8.7 s

  • SM Higgs: VBF, Htt Backgrounds:Zjj, tt

    ATLAS-2008 analysis:two forward jets, central jet vetotwo leptons (e, m, or t-jet) and METinv. mass mtt built from l, (l or t-jet), and pTmis in collinear approximation (works quite well, despite multiple neutrinos present)

    now qqH, Htt is gives significance below 5s (despite including KNLO)Htt is behind HggATLAS and CMS now agree HttpTmismm

  • SM Higgs: HWW2l2n Backgrounds:WW, tt, Wt(b), WZ, ZZ ggWW (box)

    CMS-2006 analysis:KNLO(pTWW)cuts: e/m kinematics, isolation, jet veto, MET counting experiment, no peakbackground from a control sample:signal: 12

  • SM Higgs: VBF, HWW2l2n Backgrounds:tt, WWjj, Wt

    Old ATLAS Analysis:2 high pT leptons + MET2 forward jets (b-jet veto)central jet vetocounting experiment, no peakbackground from data:Signal: all cutsControl sample: no lepton cutsResult: better than inclusive WW 2008: updates expected from ATLAS and CMSATLASMH=160 GeVHWWe Signal Region Control Sample

  • SM Higgs: HZZ4l Backgrounds:ZZ, Zbb, tt

    CMS-2006 analysis:NLO cross sectionsZZ:4-lepton mass dependent KNLO(m4l), ~1.35NNLO ggZZ box diagram, ~0.2 wrt LOcuts: isolation, vertex, e/m kinematics, m4l peakcontrol samples for ZZ background: Z-peak (Z and ZZ production are very similar) - preferredsidebands (low statistics, shape is not trivial)Data-driven methods to measurelepton reconstruction efficiencyisolation cut efficiency per eventvertex cut efficiency per eventfull treatment of systematic errors (small effect)

    for a broad search in a 110-600 GeV mass window, the look elsewhere effect de-rates significance by about 1 unit

    2008: updates expected from ATLAS and CMSCMS 2006CMS 2006H ZZ4m

  • SM Higgs: ttH, Hbb Early projections: might be observable already at L=30 fb-1

    CMS-2006 analysis: systematic error control at a percent level is needednot feasible... ATLAS-2008 analysis: same conclusions ttH is (was?) the best bet to see HbbCMS 2006L=60 fb-1ttH, Hbbcurrentestimate ofbackgrounduncertaintiesjet energy scale (3-10%)jet energy resolution (10%)b/c-tag efficiency (4%)uds/g-tag efficiency (10%)luminosity (3%)mH = 120 GeV L = 30 fb-1 2008mH = 120 GeV L = 30 fb-1 2008

  • Standard Model Higgs: Summary Benchmark luminosities (CMS+ATLAS):0.1 fb-1: exclusion limits will start carving into SM Higgs cross section0.5 fb-1:discoveries become possible if MH~160-170 GeV5 fb-1:SM Higgs is discovered (or excluded) in full rangeATLAS update should become available this year

    CMS+ATLAS will need approximately half-luminosity in comparison to a single experiment

  • MSSM Higgs: what we know from theoryOne doublet of Higgs pseudo-scalar fields is replaced with twoone couples to up-fermions and has vev=vuthe other to down-fermions and has vev=vd which allows for cancellation of the higgsino triangular anomaly loops2x4-3=5 physical scalar fields/particles: h, H, A, Hproperties at tree levelfully defined by 2 free parameters: mA, tanb=vu/vd CP-odd A - never couples to Z and W:- decays: bb, tt (and tt for small tanb)CP-even h and H are - SM-like in vicinity of their mass limits vs mA- large tanb enhances coupling to down fermions: b/t become very important! suppresses coupling to Z and WH strongly couples to tb and tn all Higgs bosons are narrow (G
  • MSSM Higgs: what we know from theory*Suggested by Carena et al., Eur.Phys.J. C26, 601(2003) Loop corrections give sensitivity to the rest of SUSY sector Special benchmark points*:max stop mixing (mh-max): maximizes mhmh < 133 GeVLEP results are least restrictiveno mixing: opposite extreme to abovemh < 116 GeVgluophobic h ggh production is suppressed (top+stop loop cancellation)mh < 119 GeVsmall aeff (mixing of Fu/Fd): htt and bb BRs are suppressed even for large tanb mh < 123 GeV

  • What we know experimentally: LEP (1)mh-max scenariomakes LEP resultsleast restrictivedotted line expected limitlight green 99% CL, dark green 95% CLyellow theoretically not accessible

  • What we know experimentally: LEP (2)mh-max scenariomakes LEP resultsleast restrictivedotted line expected limitlight green 99% CL, dark green 95% CLyellow theoretically not accessible90 GeV

  • What we know experimentally: Tevatrontanb~40

  • MSSM Higgs boson: h, H, A productionx-sections are comparable or larger than SM (dotted line)bb(h/H/A) production is very important

    h H Ah H Atanb=3tanb=30

  • MSSM Higgs: SM-like signatures CMS-2006:better detector simulationsystematic errors includedcontours recessed w.r.t. earlier projectionsATLAS-2003:no systematics includedupdates are coming out this summerATLAS2006

  • MSSM Higgs: heavy neutral H, A (F)given the H/A mass degeneracy, they are often referred to as F production in association with bb (especially good at large tanb)Decays (large tanb): bb-decay mode (~90%) is overwhelmed with QCD background tt-decay mode (~10%) is the best bet mm-decays (~0.03%) allow for direct measurement of G

    bbF, Fbbsignal bbF, Fmm bbF, FttCMS, 60 fb-1mh-maxmA=600 GeVtanb=50

    bbF, Fbb mbb (GeV)

  • MSSM Higgs: heavy neutral H, A (F)CMS 2006

  • MSSM Higgs: Heavy H Heavy H (M>mtop):production via ggtbH and gbtHtjjbH tb (BR~80%) overwhelmed by bkgd H tn (BR~20%) backgrounds: tt+jets, tW+jets, W+jets

    HtbCMSH tb and t(jjb or lnb)

  • MSSM Higgs: Light HLight H (M
  • MSSM Higgs: H summary

  • Combining all together MSSM Higgs or SM Higgs?

    SM-like h only:considerable areaeven at L=300 fb-1

    Any handles?measure branching ratios?decays to SUSY particles?SUSY particle decays?

  • MSSM Higgs or SM Higgs?Decays to SUSY:

    H c20c20 (l+l-c10)+(l+l-c10)Signature:Four leptonsLarge METMsleptons=250 GeVATLAS300 fb-1BR for different channels: R = BR(hWW) / BR(htt) D=|RMSSM-RSM|/sexpimentalCMSCMS

  • MSSM Higgs: other benchmark points?ATLAS studies (c. 2003):preliminary (no syst)all four special points are well covered at L=30 fb-1main workhorse: SM-like VBF with tt-decays

    caveat for small aeff: decoupling from tt is compensated by WW enhancement

  • MSSM Higgs: yet another twistCP-violation in Higgs sector

    complex couplings:mass eigenstates H1, H2, H3 are mixtures of h, H, Aproduction/decay modes changenew benchmark point CPX (maximum effect) suggested by Carena et al., Phys.Lett B495 (2000) 155new parameterization: (MH, tanb) uncovered holes remain more studies neededATLAS preliminaryVBF Htt, WW bbH, Htt, mmtbH and tH, Htn

    ATLASL=30 fb-1not excludedat LEP!

  • SummaryStandard Model Higgs:0.1 fb-1 exclusion limits will start carving into SM Higgs cross section0.5 fb-1discoveries become possible if MH~160-170 GeV5 fb-1SM Higgs is discovered (or excluded) in full rangeforerunner search channels: WW, ZZ, gg

    MSSM Higgs:nearly full (mA, tanb)-plane is covered at L~30 fb-1forerunner search channels for h, H/A, H: gg, tt, tn (assocd b/t important) there is a serious chance to see only a SM-like Higgs