Andrea Bocci Riccardo Ranieri Massimiliano Chiorboli Alessia Tricomi Catania Lepton Tag Andrea Bocci Riccardo Ranieri INFN and Università di Firenze Massimiliano Chiorboli Alessia Tricomi INFN and Università di Catania CMS Tracker Week bTau Meeting 20th July 2004

Soft Lepton Tag Based on identification of the soft leptons from semileptonic B-meson decays we studied only leptons=muons case Efficiency of soft lepton tagging limited by the fraction of B-meson decays containing leptons (17%) Provide a valuable complement with respect to the impact parameter tagging Preliminary studies at parton level presented at bTau Workshop in Bari (28th May-1st June) http://agenda.cern.ch/askArchive.php?base=agenda&categ=a041643&id=a041643s5t13%2Fmoreinfo%2Fsoftleptontagging.ppt Now first very very preliminary results with ORCA reconstruction bTau Meeting 20th July 2004 Catania Lepton Tag

The test samples di-jets from Christian’s test samples 2500 b, 4750 c, [5000 udsg] 80<pT[GeV/c]<120 no pileup QCD jets for ttH background (6500 evts processed) 120<pT[GeV/c]<170 cross section: σ=3.82x10-4 mb Kinematic Selection: ε=5.70x10-2 at least 4 jets ΣETjet>300 GeV jets: ET1,2>40 GeV; ET3,4>30 GeV more details from Susannna’s talk on MC requests for ttH channel studies http://cmsdoc.cern.ch/cms/Physics/btau/management/2003/ talks/030603/Susanna.pdf ^ - ^ - bTau Meeting 20th July 2004 Catania Lepton Tag

Reconstruction Studies done with ORCA_8_2_0 Reconstruction of RecMuon objects L3 Muon Reconstructor RecQuery query ("L3MuonReconstructor"); no further thresholds applied Reconstruction of JetWithTracks objects L2 Kt jet algorithm RecQuery jetFinder ("PersistentJetFinder"); jetFinder.setParameter ("JetAlgorithm", 4); // Kt=4 Tracks in cone ∆R<0.3 around jet axis RecQuery query ("BTagJetWithTracksAlgo"); query.setComponent ("JetFinder", jetFinder); query.setComponent ("TrackFinder", RecQuery(“CombinatorialTrackFinder”)); query.setParameter ("deltaRCut", 0.3); bTau Meeting 20th July 2004 Catania Lepton Tag

Monte Carlo Truth Muons Jets information on the origin of the muon (i.e. “mother” particle of the generated muon) information on the origin of the decay chain (i.e. the particle which originates the decay chain) to separate bμ from bcμ some problems with u,d,s,g, results need better understanding Jets we used Christian’s BReco/BTagMCTools package associates main parton to the reconstructed jet and assigns jet flavour some modifications inside JetIdentifier and MCParton/LundCode classes bTau Meeting 20th July 2004 Catania Lepton Tag

L2 Jet Axis Resolution - from ttH QCD background Jet axis η-φ measurements resolution improved with tracks weighted mean on tracks pT, see DAQ-TDR section 15.6.3.1 before: σ(η)=0.068 σ(φ)=0.060 after: σ(η)=0.039 σ(φ)=0.036 bTau Meeting 20th July 2004 Catania Lepton Tag

Muon pTrel and pTrel,excl Entries/bin Entries/bin Muon transverse momentum relative to jet axis left: pTrel relative to measured jet momentum direction vector pjet direction right: pTrel,excl relative to jet momentum lepton excluded vector pjet-pμ direction    bTau Meeting 20th July 2004 Catania Lepton Tag

Direct vs Cascade b decays pTrel,excl>0.8 GeV/c pTrel>0.8 GeV/c Efficiency of bμ chain versus Rejection of bcμ chain bTau Meeting 20th July 2004 Catania Lepton Tag

b-c comparison pTrel>3.2 GeV/c pTrel,excl>3.2 GeV/c Efficiency of bμ+bcμ versus Rejection of cμ bTau Meeting 20th July 2004 Catania Lepton Tag

Conclusion excerpt from ToDo list (bTau Workshop): First step: Start with muons Look for muon inside jet tracks and evaluate pTrel or pTrel,excl and IP for muon candidate pTrel and pTrel,excl done but… problems with samples too few events MC info on u,d,s,g to be better understood The bulk of the code is there, we miss only the last point: Impact Parameter coming soon WE NEED MORE EVENTS !!! bTau Meeting 20th July 2004 Catania Lepton Tag