1 / 14

Search for MSSM neutral Higgs bosons in the decay channel A/H→ μ + μ - with the ATLAS detector

Search for MSSM neutral Higgs bosons in the decay channel A/H→ μ + μ - with the ATLAS detector. Giorgos Dedes , Nectarios Benekos , Sandra Horvat , Sergey Kotov, Hubert Kroha, and Susanne Mohrdieck – M ö ck Max-Planck-Institut f ü r Physik, M ü nchen

maik
Download Presentation

Search for MSSM neutral Higgs bosons in the decay channel A/H→ μ + μ - with the ATLAS detector

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 for MSSM neutral Higgs bosons in the decay channel A/H→μ+μ-with the ATLAS detector Giorgos Dedes , Nectarios Benekos , Sandra Horvat , Sergey Kotov, Hubert Kroha, and Susanne Mohrdieck – Möck Max-Planck-Institut für Physik,München DeutschePhysikalischeGesellschaft, Dortmund 2006

  2. Outline • The bbA, A->m+m- decay channel • Muon distributions (ATLFAST – Full Simulation) • b-jet distributions (ATLFAST – Full Simulation) • Analysis results • Cut optimization • Additional cuts – improvements • Summary

  3. Processes • bbH/A, H/A-> m+m- for tanb = 30 , L= 30fb-1

  4. Data Samples ATLFAST • Pythia • No filters Full Simulation • Pythia bbA: MultiLeptonFilter: • Generated only events with plT > 5 GeV , |hl|<2.7 tt: HiggsMultiLeptonFilter: • Generated only events with mll> 180 GeV, plT > 5 GeV , |hl|< 2.7 • Approximately 10% of events passed in the specified mass range

  5. ATLFAST FullSim Muon Reconstruction (bbA sample, 300 GeV) Dpt/pt of matched muons Deta/eta of matched muons sFull = 3.4% Average muon reconstruction efficiency ~ 90% sATLFAST = 3.2% Deta/eta of matched muons Efficiency in pt ATLFAST (8.7.0): CBNT Full sim (10.0.4): AOD • high-pt muons • pT > 5 GeV , |h|< 2.7 • no muon isolation MeV Efficiency in eta Efficiency in phi

  6. Dpt/pt of matched bjets Deta/eta of matched muons ATLFAST FullSim b-jet Recostruction (bbA sample, 300 GeV) sATLFAST = 18% sFull = 24% Dphi/phi of matched bjets Efficiency in pt ATLFAST (8.7.0): CBNT Full sim (10.0.4): AOD • pT > 15 GeV , |h|< 2.5 • Likelihood b-tagging variable used (>0.9) • Gen_AOD container for truth MeV Efficiency in eta Efficiency in phi • Full simulation: Average b-jet efficiency of ~ 45% • ATLFAST: Average b-jet efficiency of ~ 35%

  7. ATLFAST FullSim Muon/b-jet Distributions(bbA sample, 300 GeV) • Very good agreement between fast and full simulation Single muon pt Single muon phi Single muon eta Normalized number of events MeV Number of reco muons bjet pt H pt MeV MeV bjet phi bjet eta Number of reco bjets

  8. ATLFAST FullSim ETmiss Distributions • In 10.0.4 data contribution from muons made ETmiss broader MET_Calo + MET_Cryo + MET_Muon bbA sample • The contribution in missing energy from the muon spectrometer is- p2mx(y) We correct by adding this value to MET_Topox(y) + MET_Cryox(y) instead of MET_Muonx(y) MeV MET_Topo + MET_Cryo + MET_Muon bbA sample MeV MET_Topo + MET_Cryo + reco dimuon PT MET_Topo + MET_Cryo + MET_TruthMu bbA sample bbA sample MeV MeV

  9. pT > 20 GeV , trigger selection pTmiss< 20 GeV 2. pTm> 20 GeV pT /MeV pTmiss /MeV pTmiss < 20 GeV pT2m< 100 GeV N(b-jets) > 0 pT2m< 100 GeV 3. 4. Event Loop tt N(b- jets) = 0 N(b- jets) > 0 bbA pT2m/MeV m2m = mA±dm m2m = mA±dm Selection Cuts (TDR) Fully simulated data 1. Normalized number of events

  10. bbA tt bbA + tt bbA tt bbA + tt Z Results – TDR cuts • bbA, A-> m+m- for tanb = 30 , L= 30fb-1 *Z background A boson invariant mass (ATLFAST) A boson invariant mass (Full Sim) MeV MeV

  11. bbA tt bbA + tt bbA tt bbA + tt Z Results – TDR cuts • bbA, A-> m+m- for tanb = 30 , L= 30fb-1 *With Z background included H/A boson invariant mass (ATLFAST) H/A boson invariant mass (Full Sim) MeV MeV

  12. bbA (full) tt (full) bbA (fast) tt (fast) Cuts Optimization • We tune the selection cuts in fast and full simulation by maximizing signal/background ratio for each step Normalized number of events pTbjet /MeV

  13. bbA tt Additional Cut (in FullSim) • Muons from A are mostly back to back in the phi plane (single body decay) Δφ-> 3.14 • In the case of tt background this is not so pronounced -> broader distribution Muons Δφ Normalized number of events • The value of this cut is obtained through the same method for optimizing signal/background ratio Δφ > 2.7

  14. Summary • Study of the A(H) discovery potential in the A -> μ+μ-decay channel , using ATLFAST and fully simulated data • ATLFAST and Full simulation are in good agreement except for b-jet efficiency (better in fullsim) and Etmiss (correction applied) • Selection cuts were optimized leading to the improvement of the signal significance • Additional selection on pTbjet and Δφμμ used and improved signal significance

More Related