Catania Lepton Tag Andrea BocciVitaliano CiulliRiccardo Ranieri INFN and Università di Firenze Alessia Tricomi INFN and Università di Catania CMS CPT Week - b Meeting 3 rd November 2004

b Meeting CPT Week 3 rd November 2004 Catania Lepton Tag IIRiccardo Ranieri 2 Soft Lepton Tag –Based on identification of the soft leptons from semileptonic B-meson decays leptons=muons  we studied only leptons=muons case –Efficiency of soft lepton tagging limited by the fraction of B-meson decays containing leptons (  20%) –Provide a valuable complement with respect to the impact parameter tagging very very preliminary –Some very very preliminary results with ORCA reconstruction already presented at b τ meeting during July Tracker Week » 955&id=a042955s1t7%2Fmoreinfo%2FCataniaLeptonTag.ppt

b Meeting CPT Week 3 rd November 2004 Catania Lepton Tag IIRiccardo Ranieri 3 The test samples –QCD jets from Christian’s test samples  2500 “b”, 4750 “c”, 5000 “udsg”  80<p T [GeV/c]<120  no pileup –some problems related to the samples: 1.Not well defined separation between signal and background –“udsg” means no requests: this sample contains also c or b jets depending on c/b quark production probability –“c”(“b”) means at least one c(b) quark in the final state: this sample is pure QCD enriched in c(b) quark content 2.Variable number of jets –we have not under control the number and flavour of jets we expect to see »problems in debugging algorithms –if jets are separated in E T bins too few jets per bin ^

b Meeting CPT Week 3 rd November 2004 Catania Lepton Tag IIRiccardo Ranieri 4 Monte Carlo Truth Muons –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 and c → μ from b → c → μ Jets BReco/BTagMCTools –we used Christian’s BReco/BTagMCTools package –associates to the reconstructed jet the main parton within ΔR(η,φ)<0.3 and assigns jet flavour JetIdentifier MCPartonLundCode  some modifications inside JetIdentifier and MCParton / LundCode classes

b Meeting CPT Week 3 rd November 2004 Catania Lepton Tag IIRiccardo Ranieri 5 Modified BTagMCTools –JetIdentifier.h HepLorentzVector MCParton  added methods to return not only the HepLorentzVector (Energy-Momentum) of the three partons, but also the partons themselves to access all the MCParton ’s methods too MCParton mainParton(){return m_MainParton;} MCParton heaviestParton(){return m_HeaviestParton;} MCParton closestParton(){return m_ClosestParton;}

b Meeting CPT Week 3 rd November 2004 Catania Lepton Tag IIRiccardo Ranieri 6 Modified BTagMCTools –JetIdentifier.cc MCParton  inside the loop to assign the most suitable MCParton to the jet, partons with PYTHIA status = 3 are excluded –example: Gluon Fusion gg → bb event: - E X C L U D E D E X C L U D E D

b Meeting CPT Week 3 rd November 2004 Catania Lepton Tag IIRiccardo Ranieri 7 Modified BTagMCTools –MCParton  mother and grandmother HEP-PID and top quark decay intgetMotherLundCode() const {return motherLundCode;} intgetGrandMotherLundCode() const {return grandmotherLundCode;} bool getIsFromT() const {return isFromT;}  Gluon Splitting Finder –loop on PYTHIA lines to find qq pairs from gluon common mother »at least a gluon in PYTHIA event (lines 3 or 4 or 5 or 6 or 7 or 8) »search for parton-antiparton with PYTHIA status≠3 “daughters” of the previous gluon »both q and q are labelled as coming “fromGluonSplitting” –too much PYTHIA-dependent –already passed to Pisa people… waiting for feedback… - -

b Meeting CPT Week 3 rd November 2004 Catania Lepton Tag IIRiccardo Ranieri 8Reconstruction –Studies done with ORCA_8_2_0 RecMuon –Reconstruction of RecMuon objects  L3 Muon Reconstructor –RecQuery query ("L3MuonReconstructor"); –no further thresholds applied JetWithTracks –Reconstruction of JetWithTracks objects Kt  L2 Kt jet algorithm –RecQuery jetFinder ("PersistentJetFinder"); –jetFinder.setParameter ("JetAlgorithm", 4); // Kt=4 ∆R<0.3  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);

b Meeting CPT Week 3 rd November 2004 Catania Lepton Tag IIRiccardo Ranieri 9 Reconstructed Muons  Association between RecMuon’s and TkSimTrack’s –93% of the times we are able to say what is the simulated particle reconstructed as a muon Sim Track Rec Muon μ±μ±μ±μ±639 π±π±π±π±123 Κ±Κ±Κ±Κ±80 other14 not-ass68 Total924 Entries/bin

b Meeting CPT Week 3 rd November 2004 Catania Lepton Tag IIRiccardo Ranieri 10 Reconstructed Muons  We can study the “life” of the RecMuon associated to a SimTrack –PYHTIA list navigation, decay chains… –for the moment we are not able to reconstruct the story of PYTHIA “stable particles” (GEANT decays) Entries/bin here there are both b → c → μ and c → μ

b Meeting CPT Week 3 rd November 2004 Catania Lepton Tag IIRiccardo Ranieri 11 L2 Jets corrected E T  Reconstructed L2 Jets with E T >40 GeV –jet flavour from MC association 80%b/c –more than 80% of b/c jets are selected –jet η and φ recalculated with tracks »improved resolution from 0.05 to 0.03 Entries/bin Jet Flavour L2 Jets [no E T cut] L2 Jets [E T >40 GeV] b c uds g Total

b Meeting CPT Week 3 rd November 2004 Catania Lepton Tag IIRiccardo Ranieri 12 Gluon Splitting  Fraction of jets coming from Gluon Splitting (GS) –sample: selected L2 jets E T >40 GeV b/c –50% of b/c jets come from GS Jet Flavour L2 Jets from GS L2 Jets not from GS L2 Jets Total b c uds g Total

b Meeting CPT Week 3 rd November 2004 Catania Lepton Tag IIRiccardo Ranieri 13 Number of L2 Jets  4 bins in jet E T  light-flavoured jets have lower E T than b/c

b Meeting CPT Week 3 rd November 2004 Catania Lepton Tag IIRiccardo Ranieri 14 L3 Muons inside L2 Jets  A L3 Muon is associated to the L3 jet if ΔR(η,φ)<0.5 75% –691/924=75% of L3 Muons are inside L2 Jets –Fraction of 40<E T [GeV]<120 jets with muons: b 12.9%c6.2% » b 12.9%c6.2% uds0.88%g1.2% » uds0.88% g1.2% L2 Jet Flavour [E T >40 GeV] L3 Muons ΔR(η,φ)<0.5 [no HLT cut] b313 c178 uds58 g142 Total691 Statistical Error: ±0.01

b Meeting CPT Week 3 rd November 2004 Catania Lepton Tag IIRiccardo Ranieri 15 Where are generated b muons? 494  494 MC generated b Muons are inside L2 Jets [E T >40 GeV] –Fraction of GeV/c, |η|<2.5) coming from b mesons/baryons decay: b 18.6%c<0.1% » b 18.6%c<0.1% uds0.26%g0.2% » uds0.26% g0.2% L2 Jet Flavour [E T >40 GeV] MC b Muons ΔR(η,φ)<0.5 [|η| 0.5 GeV/c] b452 c0 uds17 g25 Total494 Statistical Error: ±0.01

b Meeting CPT Week 3 rd November 2004 Catania Lepton Tag IIRiccardo Ranieri 16Conclusions lotWe have a lot of work to do and problems to solve simplerA simpler di-jet event sample (DAQ-TDR like) would help to debug our code