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Higgs Searches with 1 fb -1

Higgs Searches with 1 fb -1. Per Jonsson Imperial College London On behalf of the Higgs Group. D-Zero Workshop, Vancouver 13-18 June 2005. Outline. Status/plans for 1 fb -1 of data: Muons/Electrons: W/Z + jets WH->l n bb H->WW (*) ZH->llbb Jets: Z->bb ZH-> nn bb bbh->bbbb

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Higgs Searches with 1 fb -1

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  1. Higgs Searches with 1 fb-1 Per Jonsson Imperial College London On behalf of the Higgs Group D-Zero Workshop, Vancouver 13-18 June 2005

  2. Outline • Status/plans for 1 fb-1 of data: • Muons/Electrons: • W/Z + jets • WH->lnbb • H->WW(*) • ZH->llbb • Jets: • Z->bb • ZH->nnbb • bbh->bbbb • Higgs searches with t‘s • Summary

  3. W/Z+jets (G.Hesketh, T.Nunneman, B.Tiller) Z->mm incl. jet mult. • Test of QCD but also main background to many Higgs searches • “First generation” analysis of Z->ee + jets to be published w. p14 data • Plan to cover both electron and muon channels of W/Z w. p17 data: • Developing all analysis in CAF • Understanding of p17 jets limiting factor • p14 results for Moriond • Preliminary result w. p17 for next summer

  4. WH->lnbb &TC (G.Bernardi, H.Kim, L.Sonnenschein, S.Trincaz-Duvoid, J.Yu, L.Feligioni, M.Narain, S.Desai, J.Hobbs) e channel New WH results: • 382 inv. pb (electron channel) • Wbb limit: 4.6pb vs. 6.6pb published with 174pb^-1 • 371 inv. pb (muon channel) • Wbb limit: 4.1pb Goals: • WH analyses e + mu channel preliminary combination for EPS • Technicolor publications on Pass2 data • Measure Wbb (e channel) w. 1 fb-1 : • Gain ~10% sensitivity w. looser b-tag • Also expect gain from b-JES, tau channel, NN mu channel

  5. H->WW(*) & ZH->llbb (Q.Li, J.Elmshauser, M.Hohlfeld, M.Titov, J.Heinmiller, N.Varelas, Y.Mutaf, H.Dong) • H->WW(*) • PRL draft based on 300-325 pb-1 under EB review • New p17 analysis to start soon • Expect improvements from: • Advanced analysis techniques • Lepton ID and muon resolution • Bkg understanding • ZH->llbb plans for 1fb-1: • Z + b-jet cross section • Z + b/Z + j measurement • Z + bb and ZH cross section limits • Improvements (ZH->mmbb): • Looser b-tag: x2.4 • Muon isolation:x1.5 • Start p17 analysis w. CAF in Sept. ZH->mmbb: Improved sensitivity w. x-loose JLIP and opt. muon isolation

  6. Z->bb (P.Jonsson, A.Jenkins, G.Davies, A.Haas, C.Johnson) v12 Data Signal MC • Important for b-jet energy scale, light Higgs searches, bb mass resolution, b-tagging • p14 Pass2 analysis w. note in preparation: • aim to complete analysis for publication • then on to p17 analysis: • Expect ~1400 Z->bb events w. 1 fb-1 Observe ~420 +/- 145 events Systematic errors being worked on

  7. ZH->nnbb (M.Petteni, M.Tomoto) • First results shown at Moriond ‘04: • V12, pass1 data, 261 pb-1 • Working on improved pass2 analysis: • Looser b-tags, QCD cuts • x2 Increased sensitivity • Publish as soon as possible • Then move on to p17 analysis with CAF: • Room for improvement of analysis: • Hadronic calibration expected to have large impact • Aiming for Moriond ’05: • Tight schedule with p17 JES/BID availability Major limitation of current analysis is L1 trigger acceptance: RunIIb trigger upgrade will bring significant improvement

  8. bb(h/H/A)->bbbb(M.Michaut, B.Tuchming, A. Haas, T.Scanlon, J.Rani, A.Kharchilava) • Pass1 p14 analysis (260 pb-1) submitted to PRL • Almost set up to start p17 analysis: • Switch to CAF by July • Ready with full 1 fb-1 analysis for Moriond • Expected improvements to the analysis: • Neural Network b-tagger: • 20% eff.== +107% luminosity • SL tagger • Jet energy resolution: • Cal-track jet: • 15% less bkg. == + 18% luminosity • Better JES • Low pT jet reco/ID efficiency • Lower jet pT Threshold in p17 (8 GeV -> 6 GeV) • Opt. jet reconstruction alg. for low pT • Smaller uncertainties • Add more triggers and topological variabels • In total expect improved reach from: • tanb > 60 to tanb > 34 for mH = 90 GeV

  9. pre-TAUOLA fix post-TAUOLA fix Higgs Searches with t‘s Polarization in p14 TAUOLA was wrong • bb(h/H/A)  bb bblhad • A. Goussiou, Y. Pogorelov, P. Svoisky • Plan on p14 pass2 publ. end of 2005 • Then p17 analysis • bb bbhadhad • Y. Hu • p14 results for winter 2006 • Then extend to p17 • H   had • S. Kelly, M. Owen, S. Soldner-Rembold • P14 pass2 analysis just starting • Prel. results winter 2006 • Charged Higgs • A. Pompos, A. Sopzac • H++H- -  : marginal w/ 1fb-1 • M. Owen, S. Soldner-Rembold MC samples must be regenerated w. p17: high priority

  10. Triggers Higgs trigger concerns: - Risk of getting Higgs triggers prescaled at high luminosities • mu+jet special concern • Need low pT efficiency - New set of triggers in v14 - New purely track/muon based ZBB triggers at L1/L2 ~ STT IP tracks at L2 ~ L3 filters for both W/ZH and Z->bb • Newly designed single and di-tau triggers ~ Hope to run them unprescaled to high luminosities Example: WH(mnbb) analysis: Large gain in combining single muon and mu+jet triggers. Adding Higgs triggers results in further gain of about 14% in v13

  11. Summary • Moving all Higgs analyses to p17, CAF and the 1 fb-1 dataset: • Aim to deliver quick results short time after data available • Tau analyses are starting to become an important part of the Higgs searches at D0 • We hope to contribute to more efficient triggers at RunIIb • Combination effort of SM searches are about to start

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