1 / 13

Search of the Higgs boson in the WW (*) decay channel with the CMS experiment

Search of the Higgs boson in the WW (*) decay channel with the CMS experiment. We are ready to go !. Lake Louise Winter Institute. Ezio Torassa - INFN Padova. 18 th - 23 th February 2008 Alberta , Canada. On behalf of the CMS collaboration. Higgs production at the LHC.

susan
Download Presentation

Search of the Higgs boson in the WW (*) decay channel with the CMS experiment

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Search of the Higgs boson in the WW (*) decay channel with the CMS experiment We are ready to go ! Lake Louise Winter Institute Ezio Torassa - INFN Padova 18th - 23th February 2008 Alberta , Canada On behalf of the CMS collaboration

  2. Higgs production at the LHC SM Higgs production cross section including NLO QCD corrections CMS Physics TDR Vol 2 Ezio Torassa – INFN Padova

  3. Higgs branching ratios CMS Physics TDR Vol 2 For Higgs masses above 135 GeV the main decay modes are those into WW(*) and ZZ(*) (under 135 GeV b/c quarks and t+t-) The Higgs coupling constants to fermions and bosons are proportional to the particle masses: Ezio Torassa – INFN Padova

  4. Signal and Backgrounds • The signal is characterized by: • - two high Pt isolated leptons • missing Et • no high energy Jet • angle correlation between WW Continuumproduction of WW pairs Wt DY Ezio Torassa – INFN Padova

  5. Monte Carlo simulation Higgs boson signal samples were generated using the LO PHYTIA Monte Carlo. The events were reweighted to match expectation from NLO. k(pT) factors were calculated with the MC@NLO Monte Carlo. The total NLO cross section is rescaled considering NLO calculations. The same procedure was used for the dominant irreducible WW background. For the other backgrounds the inclusive k factor was used: kinc = ∫ k(pT) dpT and Wt were produced using the TopRex Monte Carlo Ezio Torassa – INFN Padova

  6. The CMS recent H→WW analysis Standard Model Higgs Discovery Potential of CMS NOTE 2006/047 CMS in the H→WW→lnln channel Systematic uncertainties of the top background CMS NOTE 2006/048 In the H→WW channel Physics study of the Higgs decay channel CMS NOTE 2006/055 H→WW(*)→2m2n Search for a Light Standard Model Higgs boson CMS NOTE 2006/114 in the H→WW(*)→enen channel Search for the Higgs boson in the WW(*) decay CMS PAS Hig_07_001 Channel with the CMS experiment CMS TDR vol II Cut based CMS PAS Hig_07_001 Cut based + TMVA Summary inside CMS TDR vol II Physics Performance Low Higgs Mass optimization This report => Ezio Torassa – INFN Padova

  7. H→WW analysis CMS PTDR vol. II The selection tools (mm channel ) Ptmax MET Isolation IP < 3s for each muon Jet Veto Missing ET > 50 GeV 55 GeV > ptmax > 35 GeV ptmin > 25 GeV Inv. Mass < 50 GeV D between muons < 0.8 Ptmin Inv. Mass Ezio Torassa – INFN Padova ( L = 10 fb-1 )

  8. H→WW analysis CMS PTDR vol. II Final selection mm + me + ee channels Angle between the leptons Ezio Torassa – INFN Padova

  9. control region H→WW analysis CMS PTDR vol. II Background estimation from data JET veto removed 2 b-tagged jets WW H→WW control region signal region Systematic error estimation Th. err.Det. sys.Stat. err. Tot. errors @ L = 5 fb-1 16% 17% Ezio Torassa – INFN Padova

  10. H→WW analysis CMS PTDR vol. II Luminosity for discovery at 5s Signal significance Ezio Torassa – INFN Padova

  11. H→WW analysis CMS PAS Hig_07_001 Analysis strategy cut based analysis trigger + skim pre-selection multivariate analysis • ptmin> 10 GeV, ptmax> 20 GeV • one pair of leptons with opposite charge • |η1| < 2.5, |η2| < 2.5 • MET > 30 GeV • m(ll) >= 12 GeV • Njets central <= 2 (ET > 20 GeV) Ezio Torassa – INFN Padova

  12. H→WW analysis CMS PAS Hig_07_001 Analysis strategy Classifier output for the boosted decision tree analysis Cut based analysis - mass dependent cuts optimization - optimized significance defined as: nσ (cuts) = NS / √[NB + (ΔNB)2] Multivariate analysis - test of different Multivariate Techniques: boosted decision tree (BDT) neural network classifiers (NN) Ezio Torassa – INFN Padova

  13. Conclusions • The Monte Carlo analysis preformed for the PTDR vol. II showed the SM Higgs boson could be discovered with: - less than 1 fb-1 if its mass is around 165 GeV - 10 fb-1 if its mass is between 150 GeV and 180 GeV • More detailed studies are showing that we can increase the sensibility in the low mass region with: - mass dependent cut based analysis - multivariate analysis techniques • Next results will provide exclusion limits with the 100 pb-1 misalignment scenario Ezio Torassa – INFN Padova

More Related