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Systematic studies

Systematic studies. Daniel Bloch (IReS Strasbourg). ptrel fits vs SystemD SystemD systematics mistag systematics: still to be studied. ptrel fits rely on ptrel templates. ptrel fits weakness.

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Systematic studies

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  1. Systematic studies Daniel Bloch (IReS Strasbourg) • ptrel fits vs SystemD • SystemD systematics • mistag systematics: still to be studied D. Bloch (IReS Strasbourg)

  2. ptrel fits rely on ptrel templates D. Bloch (IReS Strasbourg)

  3. ptrel fits weakness • The light template is estimated by taking any track in jet trigger data: it is a first approximation, but how to describe reconstruction pbs due to decay-in-flights, the pion/kaon weights, the change of direction between muon and primary pion/kaon ? • Which uncertainty on the b->mu, b->c->mu, c->mu MC templates ? • If the c/light ratio is fixed, what is its error and how does it depend on the muon or jet pt ? • Are the ptrel templates eta dependent ? • How to take into account the MC statistics in the b and c templates (it is not trivial at all) ? • Is there a correlation between the ptrel shapes and the lifetime tagging cut ? D. Bloch (IReS Strasbourg)

  4. SystemD basics • Relies on 2 taggers (JLIP and muon ptrel) and 2 samples (muon-in-jet n and subsample p with opposite JLIP tagged jet) • Allows to solve 8 equations with 8 unknowns: D. Bloch (IReS Strasbourg)

  5. SystemD assumes that: • the correlation between JLIP tag and ptrel cut is small: estimated on MC  band clfactors • the c/light ratio is the same in the full sample and in the opposite tag subsample:factor, varied around 1on real data • the b-tag efficiency is the same in the full sample and in the opposite tag subsample:factor estimated from b MC • ptrel cut has the same efficiency for c and light:estimated by varying the ptrel cut on real data and that’s all ! D. Bloch (IReS Strasbourg)

  6. JLIP-ptrel correlation in : b jets: small Et dependence:b = 1.00 in average, = 1.0050.010 . if Et<55GeV, = 0.9800.010 . if 55<Et<85GeV c and light jets:constant valuecl = 0.920.03 D. Bloch (IReS Strasbourg)

  7. double/single tag efficiency ratio are compatible, for any JLIP cut: factor  = 1.0370.005 D. Bloch (IReS Strasbourg)

  8. other SystemD factors • Same b-tag efficiency if  = 10.3  negligible systematics • Varying the ptrel cut between 0.3 and 1.0 GeV/c: seems to jump between 2 solutions in real data (for JLIP Prob<0.007)  take the average = 0.385  0.015 • Overall result: (for JLIP Prob<0.007) = 0.385 0.009 (stat) .  0.010 (b)  0.003 ()  0.015 (ptrel) = 0.385  0.009 (stat)  0.018 (syst) D. Bloch (IReS Strasbourg)

  9. Test SystemD statistical error Repeat 100,000 toy MC measurements  good agreement with the evaluated error in provided macro D. Bloch (IReS Strasbourg)

  10. mistag systematics • take negative tags as the average of jet trigger and emqcd data: use half of the difference as a systematic: ~ 5-10% relative uncertainty on mistags • Fll = positive/negative light quark tag: - compare QCD, Zuu/dd/ss and W+jets MC - test if the V0 fraction is similar in MC and data • Fhf = all negative/light negative tags in QCDMC: vary the c and b content in QCD MC ! • but Fll and Fhf systematics not yet looked at… D. Bloch (IReS Strasbourg)

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