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B-jet cross section measurement

B-jet cross section measurement

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B-jet cross section measurement

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  1. B-jet cross section measurement • Data sample • Physics distributions of real data sample •  + jet cross section measurement • PTRel templates & fits • B-jet content measurement • B-jet cross section measurement b-jet cross section measurement O. Peters

  2. Data sample - real • Real data sample • Runs 149270 – 152212 • Removed bad muon & jet runs • mu1ptxatxx_CJT5 trigger requirement • Select +jet events (0.7 cone) • Total number of events: 20502 • Total integrated luminosity: 0.6 pb-1 b-jet cross section measurement O. Peters

  3. Data sample - MC • bbbar:17k events, p10.08.01 • QCD: • 1M p10.11.00 events • 165k p10.15.01 events (|| < 2) • Currently huge statistics needed – need hack! • Extract all non-b background from QCD (/K, c, bc) b-jet cross section measurement O. Peters

  4. Data Selection (cuts) • Muon • >= 2 A-layer hits • >= 3 BC-layer hits • > 0 A-layer scint hits • > 0 B-layer scint hits • 2 > 0 (converged fit) • Jet • CHF < 0.4 • HotF < 10 • 0.05 < EMF < 0.95 • n90 > 1 R( , jet) < 0.7 mu1atxctxx_CJT5 trigger Accept b-jet cross section measurement O. Peters

  5. Physics properties b-jet cross section measurement O. Peters

  6.  + jet cross section (1) Efficiencies L1 muon L1 jet Geom. Acc. Muon reco&ID Jet Reco&ID 0.40 1.0 (>20 GeV) 0.89 0.47 0.98 R(, jet) < 0.7 pT > 6 GeV/c || < 0.8 |jet| < 0.6 Muon ID version v1.1 Jet Certification v1.2 DØ note 3949 b-jet cross section measurement O. Peters

  7.  + jet cross section (2) Limited statistics in MC & data  Looser cuts R(, jet) < 0.7 pT > 3 GeV/c || < 1 |jet| < 1 Note: lower 2 lines use tight cuts b-jet cross section measurement O. Peters

  8. PTRel: Data & MC R(, jet) < 0.7 pT > 3 GeV/c || < 1 |jet| < 1 b-jet cross section measurement O. Peters

  9. PTRel Fits 20 < Ptjet < 30 GeV b-jet content 31.9  4.8 % Ptjet > 30 GeV b-jet content 17  6.6 % b-jet cross section measurement O. Peters

  10. B-jet content b-jet cross section measurement O. Peters

  11. B-jet cross section Note: Run I data uses tight cuts b-jet cross section measurement O. Peters

  12. Conclusions • MC statistics remains a problem • Currently generating, but need better solution • Data statistics low (but available) • Current results are looking promising b-jet cross section measurement O. Peters