Update on QCD Estimation in τ + Jets Analysis: New Results from SUNY Albany
This report presents updated QCD estimation results in τ + jets analyses from William Edson at SUNY Albany. Key findings include a measured signal fraction of 0.685±0.042, with a chi-square value of 29.95 across 31 measured events. Systematic uncertainties have been evaluated, leading to new corrected results, particularly for signal fractions and uncertainties in σ values. An emphasis on correction methodologies using full simulation Monte Carlo data enhances the accuracy of the estimations presented here. This work integrates advanced statistical techniques to ensure robust results.
Update on QCD Estimation in τ + Jets Analysis: New Results from SUNY Albany
E N D
Presentation Transcript
ttbarτ + jets:Update on QCD Estimation William Edson SUNY at Albany
Only MET and Dijet Mass Fit Selection • New Results for Fit: • Signal Fraction: 0.664442±0.0418289 • Chi2: 29.953 • Meas. Used: 31 • σ: 170.884±10.7578 • New Corrected Results: • Signal Fraction: 0.685204± 0.0418289 • σ: 176.223 ± 10.7578 • Correction Systematic: ±3.87838
Top Mass Original kfac/σ(FE) from TopMC11 twiki Correction using Ref σ’s Using kfac/σ(FE) from 105200
MC Generator 1.1)fullsim mc11c POWHEG+fPythia sample 117050 (SYST_Full_117050) and MC@NLO+fHerwig sample 105200 (MC@NLO(105200)) 1.2)fullsim mc11c POWHEG+fPythia sample 117050 (SYST_Full_117050) and the fullsim mc11c ALPGEN+HERWIG samples (AlpHerwig(baseline)) 1.3) AtlFast2 mc11b POWHEG+fPythia sample 117050 (SYST_AtF_117050) POWHEG+fHerwig sample 105860 (SYST_AtF_105860)
Oddity? MET Dijet Mass
Oddity? MET Dijet Mass
for (unsigned inttfj = (tau_matched.size() - 1); tfj > 0; tfj--) { try { int REFN1 = tau_matched.at(tfj).entry(); int REFN2 = tau_matched.at(tfj-1).entry(); if( (physics->tau_BDTJetScore->at(REFN1)) > (physics->tau_BDTJetScore->at(REFN2))) { save = tau_matched.at(tfj); tau_matched.at(tfj) = tau_matched.at(tfj-1); tau_matched.at(tfj-1) = save; } } catch (conststd::out_of_range& C12_2){ std::cerr << endl << "C12.2: OUT OF RANGE ERROR: " << C12_2.what() << endl; EMERXIT = 12; continue; } }
QCD Bin/Range Range increases/decreases in steps of 20GeV Bin amount increases/decreases in steps of 5
Y(0): -0.186462 ± 0.0013857 Slope: 1.23971 ± 0.00246245 Chi2: 32.7364 NDF: 8998 Linearity Testto All Values
Linearity Testto Means Slope: 1.23772 ± 0.0351884 y-intercept: -0.184483 ± 0.0198016 Chi2: 0.00520053 NDF: 7
MC Tau Plots MC Tau Children Count MC Tau Count MC Tau Children pdgID LeptonicpdgID values: e → 11, μ → 13, τ → 15
MT Signal vs Control vs MC Backgrounds Samples Normalized to Own Integrals Samples Normalized to Sum of Integrals
Cutflow • C0: GRL • C1: Trigger • C2: Primary vertex with ntracks > 4 • C3: Electron/muon overlap • C4: Jet cleaning • C5: Lepton Veto • C6: tau n ≥ 1 • C7: njets >= 4 with eta < 2.5 and |jvf| > 0.75 • C8: MET > 60GeV • C9: MT < 80GeV • C10: >= 1 bjet • C11: Trigger matched tau n ≥ 1 and pT >= 40GeV • C12: MC tau object match
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
Chi-squared minimization cont. • σi determined using factors for: • bin error: • data • signal, MC • QCD template • other backgrounds, MC • statistical error: • data: signal region • other backgrounds, MC • signal, MC • QCD template (uncertainty of background region data and all MC background region carried through via default SumW2
Highest pTbjet reconstruction • Results for plot: • chi-square: 9.818 • p-value: 0.7753 • ndf: 14 • chi/ndf: 0.7012
2nd Highest pTbjet reconstruction • Results for plot: • chi-square: 13.66 • p-value: 0.5517 • ndf: 15 • chi/ndf: 0.9107
Dijet Mass reconstruction • Results for plot: • chi-square: 15.47 • p-value: 0.6297 • ndf: 18 • chi/ndf: 0.8594
MET • Results for plot: • chi-square: 15.87 • p-value: 0.1971 • ndf: 12 • chi/ndf: 1.323
Closest pTbjet reconstruction • Results for plot: • chi-square: 14.39 • p-value: 0.2123 • ndf: 11 • chi/ndf: 1.308
New Event Selection Verification (Only uses MC so Excludes QCD)