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The Matrix Method. Data-driven method of estimating the W →lv and QCD multijet contributions to sample S’. Lepton selection efficiency in W + jets. Use Monte Carlo to obtain ε W : l W represents the number of leptons in the Monte Carlo W+jets sample which pass the loose lepton cuts.
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The Matrix Method Data-driven method of estimating the W→lv and QCD multijet contributions to sample S’.
Lepton selection efficiency in W + jets • Use Monte Carlo to obtain εW: • lW represents the number of leptons in the Monte Carlo W+jets sample which pass the loose lepton cuts • lW’ represents the number of leptons in the W+jets sample which also pass the tight lepton cuts • εW = lW’ / lW
Lepton selection efficiency in QCD multijets • Use data sample with MET < 10 GeV to obtain εQCD: • lQCD represents the number of leptons in the QCD sample which pass the loose lepton cuts. • lQCD’ represents the number of leptons in the QCD sample which pass the tight lepton cuts • εQCD = lQCD’ / lQCD
Data samples • S contains N events which passed the preselection cuts with the loose lepton cuts. • N = NQCD + NW • S’ contains N’ events which passed the preselection cuts with tight lepton cuts. • N’ = NQCD’ + NW’ • N’= εQCD NQCD + εW NW
Number of signal and background events • The number of W→lv events in the data sample S’ is then: • NW’ = εW NW • NW’= εW (εQCDN – N’) / (εQCD – εW) • The number of QCD multijets in S’ is: • NQCD’ = εQCD NQCD • NQCD’= εQCD (N’ – εW N) / (εQCD – εW)