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ICHEP2006, EW session, July 28, 2006

Searches for the Standard Model Higgs boson at LHC A. Nikitenko, IC, London. On leave from ITEP, Moscow. CERN, Building 40. ATLAS. CMS. ICHEP2006, EW session, July 28, 2006. Emphasize will be given to the new CMS PTDR results obtained at L=2x10 33 cm -2 s -1.

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ICHEP2006, EW session, July 28, 2006

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  1. Searches for the Standard ModelHiggs boson at LHCA. Nikitenko, IC, London. On leave from ITEP, Moscow CERN, Building 40 ATLAS CMS ICHEP2006, EW session, July 28, 2006

  2. 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

  3. pp, B-Physics,CP Violation ALICE LHC : 27 km long 100m underground ATLAS General Purpose,pp, heavy ions Heavy ions, pp CMS +TOTEM

  4. The CMS Detector today at point 5 The ATLAS Barrel Toroid. End of November 2005

  5. SM Higgs mass constraints from the data and theory Experiment SM 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) The triviality (upper) bound and vacuum stability (lower) bound as function of the cut-off scale L “triviality” : Higgs self-coupling remains finite Direct limit from LEP: MH > 114.4 GeV

  6. NLO

  7. SM Higgs boson couplings and Br. ratios Djouadi, Kalinowski, Spira tree level couplings v is vev of Higgs field = 246 GeV Right bottom plot includes uncertainties from the quark masses mt, mb, mc and as(MZ)

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

  9. H->ZZ(*)->4l - golden mode (first studies in CMS in 1995) • Background: tt, ZZ, llbb (“Zbb”) • Selections : • lepton isolation in tracker and calo • lepton impact parameter, mm, ee vertex • mass windows MZ(*), MH H->ZZ->ee mm

  10. H->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 discovery eemm eemm CMS at 5s sign. CMS at 5s sign.

  11. H->ZZ->4l Signal significance: new vs old results; no big change ~ 125 GeV

  12. CP property with H->ZZ->4l d G (h) ~ H + h I + h2 A, H scalar, A – pseudoscalar, h=tan(x), x = +/- p/2 --> A C2 = s Br / sSM Br SM CMS CMS C2 needed to exclude SM h

  13. Inclusive H->gg CMS plot of the ECAL TDR time : December 1997 Went then from hybrid silicon + gas chamber tracker to all silicon tracker

  14. CMS CMS

  15. Discovery potential of H->gg SM light h->gg in MSSM inclusive search Significance for SM Higgs MH=130 GeV for 30 fb-1 * NN with kinematics and g isolation as input, s/b per event

  16. Discovery of SM H->gg in associated ttH and WH production at high luminosity Discovery of Wh, h->gg Discovery of tth, h->gg L=1034 cm-2 s-1 CMS CMS L=1034 cm-2 s-1 Significance of tth, h->gg for 100 fb-1

  17. Accuracy of the Higgs boson mass measurement with H->ZZ->4l and H->gg Stat. error only

  18. Early discovery with H->WW->2l2n • New elements of analysis • PT Higgs and WW bkg. as at NLO (re-weighted in PYTHIA) • include box gg->WW bkg. • NLO Wt cross section after jet veto • Backgrounds from the data (and theory) • tt from the data; uncertainty 16% at 5 fb-1 • WW from the data; uncertainty 17% at 5 fb-1 • Wt and gg->WW bkg from theor. uncertainty 22% and 30% after cuts: - ETmiss > 50 GeV - jet veto in h < 2.4 - 30 <pT l max<55 GeV - pTl min > 25 GeV - 12 < mll < 40 GeV

  19. Discovery reach with H->WW->2l Excluded cross section times Branching Ratio at 95% C.L. CMS Phys. TDR 2006 very similar to old results w/o syst.

  20. Luminosity needed for 5 s discoveryfor incl. Higgs boson production

  21. Discovery of qqH associated production (Weak Boson Fusion) qq->qqH

  22. (written in 2005)

  23. Jet veto (“rapidity gap”) in VBF (WW->H) production first discussed in : Yu. Dokshitzer, V. Khoze and S. Troyan, Sov.J.Nucl. Phys. 46 (1987) 712 Yu. Dokshitzer, V. Khoze and T. Sjostrand, Phys.Lett., B274 (1992) 116 From D. Zeppenfeld; talk on TeV4LHC, 2004

  24. First, full simulation analysis ofqqH, H->tt->l+jet CMS SM discovery of light h in MSSM Discovery in Standard Model

  25. Summary of SM Higgs boson discovery: Signal Significance for 30 fb-1 with K factors ATLAS h->gg sensitivity is now comparable with CMS CMS ttH, H->bb does not have even 3 s with 60 fb-1

  26. Measurement of the SM Higgs boson couplings ATL-PHYS-PUB-2003/030

  27. Conclusions • The latest simulation studies show: • Inclusive h->2g could be discovered with < 10fb-1 • almost no change in the discovery potential with H->ZZ->4l and H->WW->2l. • tth, h->bb is lost as CMS discovery channel even with 60 fb-1 • qqh, h->tt “survived” after full simulation ! The biggest discovery reach in MA-tan b • Mass measurement 0.1-1.0 % precision • Width measurement 10-5 % precision, MH > 200 GeV • CP with H->ZZ • Ratio of couplings: ~ 5-30 %

  28. BACKUP

  29. Can MSSM be distinguished from SM in the area of only light Higgs discovery ? discrepancy from the SM for light h M. Duhrssen et al.,hep-ph/0407190

  30. Total weight 12500 t Overall diameter 15 m Overall length 21.6 m

  31. Physics runs 2008-2009 First , we should “discover” Standard Model

  32. ~ 107-8 Z->ll, W->ln on tape during physics run in 2008-09 (~ 10fb-1 ?) Z, W, tt cross sections and expected number of events after trigger in CMS with 10 fb-1 J. Campbell, R.K. Ellis, D. Rainwater hep-ph/0308195 W/Z+nJ+X NLO predictions at LHC with cuts : pTl > 15 GeV |hl| < 2.4 pTj > 20 GeV |hj| < 4.5 DRlj > 0.4 DRll > 0.2 W/Z bb + X |hb| < 2.5 ~ 106 tt->m+X with 10 fb-1

  33. W/Z+nJets is very important background for Higgs at LHC Zbb,Zcc, Wbb, Wcc (W/Z+QQ+nj) are as important as W/Z+nj

  34. Discovery potential for the Higgs boson(s) in CMS is updated in comparison with Higgs Summary Note, CMS Note 2003 : • Latest trigger table • Bkg estimates from “data” and exp. systematics • Advanced generators for multi-jet events: ALPGEN, MadGraph, CompHEP, TopRex • almost all analyses use full G4 simulation data

  35. New elements of PTDR 2006 analysis: - splitting into categories depending of R9=E(3x3)/Esc and h regions - usage of LLR for discovery, systematic - “optimized analysis” – NN with kinematics and g isolation as input, s/b per event 1 fb-1 1 fb-1 barrel with large R9 barrel with small R9 1 fb-1 1 fb-1 endcaps with large R9 endcaps with small R9

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