ttbar τ + jets:Update on QCD Estimation

William EdsonSUNY at Albany

Chi-squared minimization Equation:

N(x): total number of events of type x for distribution n(x)i: number of events in bin of type x frac(Sig): fraction of N(Remain) expected to be Signal binfrac(x)i: fraction of events in bin of type x

expected from MC or template σi: uncertainty in bin i

2

i

iiii2

σ)n(OB)D)binfrac(QC*N(Remain)*frac(QCD)g)binfrac(si*N(Remain)*(frac(Sig)n(Data)χ

N(OB) - N(Data) N(Remain)

frac(Sig) - 1 frac(QCD)

Chi-squared minimization cont. σi determined by adding in quadrature

bin error: data signal, MC QCD template other backgrounds, MC

statistical error: data: signal region (times 2) data: background region other backgrounds, MC (times 2) signal, MC signal and other backgrounds combined, MC:

background region

Results Rerunning Analysis Using Old Code

Run 1: chi-squared: 26.75 signal fraction: 0.7744 +/- 0.0742

Rescale signal MC in all regions and rerun: chi-squared: 25.51 signal fraction: 0.7747+/- 0.0702

Highest pT bjet reconstruction Chi2: 14.46 NDF: 9 Chi2/NDF: 1.607

2nd highest pT bjet reconstruction

Chi2: 7.534 NDF: 9 Chi2/NDF: 0.8371

Dijet reconstruction Chi2: 7.524 NDF: 11 Chi2/NDF: 0.6840

Closest Top mass reconstruction

Chi2: 11.70 NDF: 8 Chi2/NDF: 1.463

Oddity

Back-up

Results Run 1:

chi-squared: 31.78 signal fraction: 0.7415 +/- 0.0823

Rescale signal MC in all regions and rerun: chi-squared: 30.94 signal fraction: 0.7400+/- 0.0792

Results Run 1:

chi-squared: 4.541 signal fraction: 0.9891+/- 0.1460

Rescale signal MC in all regions and rerun: chi-squared: 3.905 signal fraction: 0.9787+/- 0.1233

Highest pT bjet reconstructionJune 6 Old Code

2nd highest pT bjet reconstructionJune 6 Old Code

Dijet reconstructionJune 6 Old Code

Closest Top mass reconstructionJune 6 Old Code

Cutflow C0: GRL C1: Trigger C2: Primary vertex with ntracks > 4 C3: Electron/muon overlap, larVeto C4: Jet cleaning C5: Lepton Veto C6: njets >= 4 with eta < 2.5 and |jvf| > 0.75 C7: MET > 60GeV C8: MT < 70GeV C9: Sum ET < 500GeV C10: >= 1 bjet C11: Tau n ≥ 1, BDTScore > 0.7 C12: Trigger matched tau n ≥ 1 and pT >= 40GeV C13: MC tau object match