1. Plenary Physics Meeting, 17 June 05 Per Jonsson Imperial College London 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. Plenary Physics Meeting, 17 June 05 Per Jonsson Imperial College London 2 Outline Status/plans for 1 fb -1 of data: –Muons/Electrons: W/Z + jets WH->l bb H->WW (*) ZH->llbb –Jets: Z->bb ZH-> bb bbh->bbbb –Higgs searches with  ‘s Summary

3. Plenary Physics Meeting, 17 June 05 Per Jonsson Imperial College London 3 W/Z+jets (G.Hesketh, T.Nunneman, B.Tiller) 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 Z->  incl. jet mult.

4. Plenary Physics Meeting, 17 June 05 Per Jonsson Imperial College London 4 WH->l bb &TC (G.Bernardi, H.Kim, L.Sonnenschein, S.Trincaz-Duvoid, J.Yu, L.Feligioni, M.Narain, S.Desai, J.Hobbs) 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 e channel mu channel

5. Plenary Physics Meeting, 17 June 05 Per Jonsson Imperial College London 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->  bb): Looser b-tag: x2.4 Muon isolation:x1.5 –Start p17 analysis w. CAF in Sept. ZH->  bb: Improved sensitivity w. x-loose JLIP and opt. muon isolation

6. Plenary Physics Meeting, 17 June 05 Per Jonsson Imperial College London 6 Z->bb (P.Jonsson, A.Jenkins, G.Davies, A.Haas, C.Johnson) 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 v12 Data Signal MC

7. Plenary Physics Meeting, 17 June 05 Per Jonsson Imperial College London 7 ZH-> bb (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. Plenary Physics Meeting, 17 June 05 Per Jonsson Imperial College London 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: tan  > 60 to tan  for mH = 90 GeV

9. Plenary Physics Meeting, 17 June 05 Per Jonsson Imperial College London 9 Higgs Searches with  ‘s 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 pre-TAUOLA fixpost-TAUOLA fix Polarization in p14 TAUOLA was wrong MC samples must be regenerated w. p17: high priority

10. Plenary Physics Meeting, 17 June 05 Per Jonsson Imperial College London 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(  bb ) analysis: Large gain in combining single muon and mu+jet triggers. Adding Higgs triggers results in further gain of about 14% in v13

11. Plenary Physics Meeting, 17 June 05 Per Jonsson Imperial College London 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