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Inclusive b production at LHC with CMS

Inclusive b production at LHC with CMS. Valery Andreev UCLA June 8, 2006 CERN, 2 nd HERA-LHC workshop. cm - 2 s -1. cm - 2 s -1. Large Hadron Collider (LHC). CMS. ATLAS. Design luminosity L = 10 34 cm -1 s -1 ~ 100 fb -1 / year Pile up ~ 20 collisions/crossing

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Inclusive b production at LHC with CMS

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  1. Inclusive b production at LHC with CMS Valery Andreev UCLA June 8, 2006 CERN, 2nd HERA-LHC workshop

  2. cm-2s-1 cm-2s-1 Large Hadron Collider (LHC) CMS ATLAS Design luminosity L = 1034cm-1s-1 ~ 100 fb-1/ year Pile up ~ 20 collisions/crossing 40 MHz pp bunch-crossing rate Start-up luminosity L  1033cm-1s-1  ~ 10 fb-1/ year expected completion : mid 2007 HERA-LHC June 8, 2006

  3. The CMS detector • Onion structure: • Tracker • Calorimeters • Muon system • Precise • e, , , jets, ET • Efficient • b tagging, detection HERA-LHC June 8, 2006

  4. B production • b productionat hadron colliders • Huge cross section • Challenge for perturbative QCD • New physics searches: b jets as a signal feature HERA-LHC June 8, 2006

  5. Analysis • B production total cross section • Differential cross sections d/dpt’ d/d • Selection (b-tag) • semileptonic b-decays into muons • Background (b purity) • Trigger efficiency • Luminosity HERA-LHC June 8, 2006

  6. Event Selection B tagged jet + muon • Trigger • Level 1: single muon, Pt > 14 GeV/c • High Level (HLT) trigger, cross-channel • Muon, Pt > 19 GeV/c, |  | < 2.4 • B tagged Jet, Et > 50 GeV • B tag • Inclusive secondary vertex reconstruction in jets (C. Weiser, CMS Note 2006/014, 2006) HERA-LHC June 8, 2006

  7. B phase space • B hadron • Pt > 50 GeV/c • |  | < 2.4 HERA-LHC June 8, 2006

  8. Event selection ~4 M QCD events processed HERA-LHC June 8, 2006

  9. Level 1 trigger efficiency b, c HERA-LHC June 8, 2006

  10. High Level (HLT) trigger efficiency HERA-LHC June 8, 2006

  11. B tagging efficiency HERA-LHC June 8, 2006

  12. B jet resolution Pt > 170 GeV/c  = 12.9 %  = 5.7 % HERA-LHC June 8, 2006

  13. B tagging with muon Muon is inside jets HERA-LHC June 8, 2006

  14. B tagging with muon HERA-LHC June 8, 2006

  15. B jet-muon association efficiency ~ 75 % HERA-LHC June 8, 2006

  16. Fit results QCD events MC: 120 < Pt < 170 GeV/c Muon Pt w.r.t. the closest B jet Nb =2503 (66% Nc = 965 (26% Nudsg = 299 (8% --------- 3767 events b c Fit: udsg Nb =2750  346 Nc = 702  513 Nudsg = 329  235 --------- 3781 events HERA-LHC June 8, 2006

  17. Fit results QCD events MC: 230 < Pt < 300 GeV/c Muon Pt w.r.t. the closest B jet Nb =5250 (56 % Nc = 2388 (26% Nudsg= 1740(18% --------- 9378 events b c udsg Fit: Nb =5222  501 Nc = 2050  728 Nudsg =1778 341 --------- 9050 events HERA-LHC June 8, 2006

  18. Systematics (10 fb-1) HERA-LHC June 8, 2006

  19. Conclusions • ~16 M b events to be selected at 10 fb-1 by CMS (one year of low lumi LHC) • Up to 1.5 TeV Pt reach is expected • New test of QCD is coming HERA-LHC June 8, 2006

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