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This analysis focuses on the tt production in the lepton+jets channel using streamtest data. Preselection and selection criteria are applied, along with calibration studies using Z0 and various systematic uncertainties.
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Athena job preselection ROOT Analysis AOD User Tree Esercizio con gli streamtest data Sezione d’urto tt nel canale leptone + jets • - Versione software 12.06 • Streamtest campioni inclusivi di elettroni e muoni, L~15 pb-1 • MC tt e principali fondi (W+jets, WW, single top), LMC >> LST • Tagli semplici ed affidabili (commissioning analysis) • Studi preliminari di calibrazione usando Z0ee/mm (lepton energy scale, trigger efficiency, jet energy scale) • Studi di possibili effetti sistematici (JES, Top mass, signal simulation, bg normalization, missing Et) • Report in fase di preparazione • Per il prossimo futuro: • - Ripetere l’esercizio con FDR2 usando la versione 14 e tools di analisi piu’ recenti e standard • Migliorare e studiare meglio l’isolamento del m • Studiare le sistematiche da PDF
Selection AOD containers: Electrons: ElectronCollection Muons: MuidMuonCollection Jets: Cone4TowerParticleJets • Preselection: • - Electrons: |h|<2.5 escluso 1.37<|h|<1.52, isem == 0x800, Pt > 15 GeV; • - Muons: |h| < 1, Pt > 15 GeV; • - Jets: |h|<2.5, Pt > 15 GeV; • - Missing Et: MET_RefFinal > 15 GeV; • Preselection requires one elecron or muon • Selection: • - Level 1 and Level 2 triggers; • One lepton Pt > 20 GeV and R>0.4 respect to closest jet; • Missing Et > 20 GeV; • ≥ 4 jets with Pt > 20 GeV; • ≥ 3 jets with Pt > 40 GeV; • The 3 jets with highest vector sum Pt assigned to the top (hadronic decay) and used to reconsruct the top mass. • - Mtop < 500 GeV
Electron channel Muon channel Eff.(ttbarnohad)=0.022 Eff.(ttbarnohad)=0.057
Electron channel: comparison streamtest – MC electron Pt electron Eta Missing Et N jet electron Phi electron-jet DR Eta jet Phi jet Pt jets Pt 1°jet Mjjj Pt 2°jet Pt 3°jet
Muon channel: comparison streamtest – MC Missing Et N jet muon Pt muon Eta muon Phi Eta jet Phi jet muon-jet DR Pt jets Pt 1°jet Mjjj Pt 3°jet Pt 2°jet
Systematic uncertainties Cross section Nobs = events from streamtest data Nbg = predicted bg Lumi = integrated luminosity e = selection efficiency for tt lepton+jets or leptons Br = Branching ratio for tt lepton+jets or leptons
Calibration studies using Z0 Selection: 2 electrons or muons Lepton energy scale Mee Mmm no corr. for m-ch. +1% corr. for MC Pt jet 15-40 GeV • Jet energyscale • 1 jet balancing Z0 Pt • 80 < Mee < 100 GeV Pt jet > 40 GeV