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First setps in the tt x-section measurement using JLIP with p13

First setps in the tt x-section measurement using JLIP with p13. Sébastien Greder , D.Bloch. I. Ripp-Baudot, D.Gele (IReS Strasbourg ). Taggability B-tagging efficiency Scale factor SF b Mistag and scale factors SF hf and SF ll W+njet selected and tagged Conclusions and plans.

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First setps in the tt x-section measurement using JLIP with p13

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  1. First setps in the tt x-section measurement using JLIP with p13 Sébastien Greder, D.Bloch. I. Ripp-Baudot, D.Gele (IReS Strasbourg) • Taggability • B-tagging efficiency • Scale factor SFb • Mistag and scale factors SFhf and SFll • W+njet selected and tagged • Conclusions and plans S.Greder (IReS Strasbourg)

  2. Taggability x-check : parametrization/prediction • Sample and cuts : • E+jets, applied good runs, good lumi.blocks, • double counting, no constraints on EM • object(s), no trigger signal. • (/rooms/attic/work/elis/top/LP2003/anal/runlist_july92003.txt and • badlbn_all_july92003.txt) • Ariels’ PV cuts : Nb Tracks >= 3, |Z| < 60 cm. S.Greder (IReS Strasbourg)

  3. B-tagging efficiency in data The b-tagging efficiency has been computed with the new taggability and corres. to the p13 updated JLIP (see b-id meetings). Sample : muon-in-jet from Higgs group skim, p13.04/05, Pt(m) > 6 GeV. We get : e(b) ~ 0.40 for a JLIP cut of 1% using system8 method (x-check on the way using PtRel methods) S.Greder (IReS Strasbourg)

  4. B/C-tagging efficiency in Wbb, Wcc p14 Flavour is assigned By requiring B, D mesons or none in a 0.5 cone around jet axis B jets C jets S.Greder (IReS Strasbourg)

  5. SFb This scale factor is defined as the ratio of semileptonic b-tagging eff. in data on the MC corresponding one Data efficiency is evaluated on p13 but MC on p14 ALPGEN Wbb, WbbJ, WbbJj S.Greder (IReS Strasbourg)

  6. Mistag and scale factors SFhf and SFll Using p13 MC Qcd 40-80 S.Greder (IReS Strasbourg)

  7. Mistag and scale factors SFhf and SFll Total scale factor : SFhf * SFll As already mentioned by Flera, there is an h dependance S.Greder (IReS Strasbourg)

  8. Mistag rate for light jets Using emqcd sample S.Greder (IReS Strasbourg)

  9. W+njet in e+jet sample Inclusive number of W+nJets in e+jet sample without soft lepton veto in CC region (using code : /work/school-clued0/lphaf/wjets_sum05.tgz) Will do the same with mu+jet S.Greder (IReS Strasbourg)

  10. Conclusions abd plans • Analysis chain is nearly achieved • To do : • Get W+tt and Qcd in preselected W+nJets • Evaluate qcd and W+nj background (using p14 ALPGEN) • (pb : no (good) p14 qcd up to now ) • Compute expected rate for qcd, W+nj and tt • Analysis can move to p14 a.s.a p14 mc is ready • (tagger has been tuned but still needs some detailed • studies) • Try to get first estimate of x-section in 2 weeks S.Greder (IReS Strasbourg)

  11. Tagged events in the e+jet sample Run / Event number 176875 – 16966764 175919 – 46961265 169923 – 16396718 (tagged SVT/CSIP) 177275 - 5302321 168465 – 4399234 168516 – 262422720 176882 – 6025400 175825 – 9923900 178152 – 32384663 164040 – 19265127 175144 – 55765879 175335 - 29822900 S.Greder (IReS Strasbourg)

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