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Some JLIP systematic studies

Some JLIP systematic studies. Daniel Bloch , B. Cl ément, D. Gel é, S. Greder, I. Ripp-Baudot (IReS Strasbourg). factorization of light quark mistags mistag systematics SystemD cross-checks on MC b-tag systematics. Factorization of mistags.

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Some JLIP systematic studies

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  1. Some JLIP systematic studies Daniel Bloch, B. Clément, D. Gelé, S. Greder, I. Ripp-Baudot (IReS Strasbourg) • factorization of light quark mistags • mistag systematics • SystemD cross-checks on MC • b-tag systematics D. Bloch (IReS Strasbourg)

  2. Factorization of mistags • use the same fixed shape in all 4  ranges • only the normalization is free • factorization is valid for JLIP D. Bloch (IReS Strasbourg)

  3. Mistag systematics • mistag efficiency = ε(neg tag)x FhfxFll • ε(neg tag)syst : compare jes and emqcd data → ± 5% per Et bin • Fhf syst : vary the c and b content in QCD MC by ± 10% → Fhf varies by ± 6% for c, by ± 8% for b • Fll syst : replace QCD MC by Z →uds or W+jets, but no significant differences • Overall systematics =(5²+6²+8²) = ± 11% D. Bloch (IReS Strasbourg)

  4. Cross-checks of SystemD • Aim: test SystemD on Monte Carlo only • MC sample used: light = QCD 40+80 (516k jets: use highest pt track to mimic muons) c = Z→cc→μ + ttbar→c→μ (57k jets) b = Z→bb→μ + ttbar→b→μ (146k jets) • Use 3 “taggers": muon ptrel  0.7 GeV/c JLIP prob  0.007 on muon-jet JLIP prob  0.05 on “opposite" jet • Check the correlations between taggers • Solve the system and compare results with expectations D. Bloch (IReS Strasbourg)

  5. 8 equations / 8 unknowns 1= muon tag, 2 = JLIP tag, 3 = opposite tag ε = tag-efficiency, α/β = correlation factors • n = nb + ncl • n1 = ε1b nb + ε1cl ncl • n2 = ε2b nb + ε2cl ncl • n3 = ε3b nb + ε3cl ncl • n12 = α12ε1bε2b nb + β12ε1clε2clncl • n23 = α23ε2bε3b nb + β23ε2clε3cl ncl • n31 = α31ε3bε1b nb + β31ε3clε1cl ncl • n123 = α12α23α31ε1bε2bε3b nb . + β12β23β31ε1clε2clε3cl ncl . . . . . . . D. Bloch (IReS Strasbourg)

  6. correlations for b-jets α12 α23 α31 D. Bloch (IReS Strasbourg)

  7. results / expected vs jet Et ncl/n ε1cl (muon) ε2cl (JLIP) ε3cl (oppo) nb/n ε1b (muon) ε2b (JLIP) ε3b (oppo) nb/n ε1b (muon) ε2b (JLIP) ε3b (oppo) D. Bloch (IReS Strasbourg)

  8. b-tag systematics Using SystemD: • vary correlation coefficients within their (MC) errors : ±2.9% • vary the muon ptrel cut (from 0.4 to 1.0 GeV/c) : ±0.7% • → ±3% but take rather a conservative (?) ±5% • Use this estimate and show it on many plots: Et, , jet multiplicity,run number… D. Bloch (IReS Strasbourg)

  9. SystemD results looks stable, but difference with ptrel fits not well understood… D. Bloch (IReS Strasbourg)

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