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CMS / ATLAS production: quarkonia , cross section, correlations

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  1. CMS / ATLAS production: quarkonia, cross section, correlations Valery P. Andreev University of California, Los Angeles on behalf of the CMS and ATLAS Collaborations 12th International conference on B-physics at Hadron Machines BEAUTY09, Heidelberg, Germany 7-11 September 2009

  2. Outline • Introduction • LHC: schedule, ATLAS/CMS detectors • onia production at LHC • triggers • cross sections • polarization • b production at LHC • b tagging • cross sections • high luminosity run (PT reach) • correlations • conclusions Valery Andreev, UCLA

  3. Heavy Flavor study prospects in ATLAS and CMS vs luminosity Ο( 10 pb-1) Ο( 100 pb-1) Ο( 1 fb-1) Ο( 10 fb-1) • Cross sections for beauty, charm, onia Prompt and indirect J/Ψ, exclusive B decays • Onia production study • polarisation, correlations, Υ • bb correlations • Life time of B hadrons • high PT b production cross section • Bs oscillations • CP violation • FCNC rare decays (B μμK, Bsμμ, …) − Valery Andreev, UCLA

  4. Heavy Flavourproduction • b productionat hadroncolliders • Huge cross section • in other SM processes (top, Z, …) • Challenge for perturbativeQCD • Tevatron measurements are on top of NLO QCD calculations • New physics searches: • b jets as a signalfeature (SM Higgs, SUSY decay chains, …) • b jets as a background • onia productionat hadroncolliders • prompt quarkonia production not yet understood • Color Singlet Model, Color Octet Mechanism, NRQCD, ... • polarisation measurements challenging theory as well A.Grelli, EPS09 Valery Andreev, UCLA

  5. The CMS detector General-purpose detector • Onion structure: • Tracker • Calorimeters • Muon system • Precise • e, , , jets, ET • Efficient • b tagging, detection Valery Andreev, UCLA

  6. The ATLAS detector General-purpose detector Tile CAL LAr CAL Toroids 2T solenoid TRT and Si tracker Muon detector Valery Andreev, UCLA

  7. LHC schedule 2009-2010 http://lhc-commissioning.web.cern.ch/lhc-commissioning/luminosity/09-10-lumi-estimate.htm ~30÷45 pb-1 @ 7 TeV ~270 pb-1 @ 8-10 TeV Valery Andreev, UCLA

  8. Quarkonia production measurement at LHC (CMS) • low luminosity (start-up) conditions • Lowest possible trigger thresholds, if any • Double-muon trigger with PT > 3 GeV/c, |η| < 2.4 • Single muon trigger with threshold PT > 3,5,9 GeV/c – depends on lumi • open-muon trigger at start-up • Displaced dimuon vertex trigger • Take advantage of already aligned by cosmics tracker • close to ~ 100 pb-1 collision dataalignmentscenario • Expectation for 10 pb-1 • 250k J/Ψ • 60k bJ/Ψ X • 60k Υ Helpful in detector calibration and trigger/tracker/muon chambers commissioning Valery Andreev, UCLA

  9. Quarkonia production measurement at LHC (ATLAS) ATLAS, CERN-OPEN-2008-020 μ1 μ2 • Trigger (dimuon) • Topological dimuon trigger • μ6μ4 μ1: PT > 6 GeV/cμ2: PT > 4 GeV/c • μ4μ4 at start-up OR • single muon trigger PT > 6 GeV/c(μ4 at start-up) • dimuon trigger seeded by single muon, extended region of interest • off-line: mass and vertex cuts μ1 ATLAS J/ψ with CMS ATLAS no vtx and cτ cut Prompt J/ψ and ϒ production trigger 2μ3 μ6μ4 mass res.(MeV) 30 54 yield/10pb-1 250k 150k Valery Andreev, UCLA

  10. J/ψ production study (CMS) PAS BPH-07-002 3 pb-1 3 pb-1 Inclusive J/ψ cross section: 1-D fit to mass spectra Prompt vs non-prompt (BJ/ψ X): 2-D fit to mass spectra and pseudo-proper decay length • Systematics dominated • already at start-up • Systematics at ~15% level • Competitive with Tevatron starting with the first picobarns Valery Andreev, UCLA

  11. J/ψ and ϒ production (ATLAS) • 10 pb-1 estimate • prompt fraction selected • by vertexing, cut on • pseudo-proper time no vtx and cτ cut Polarisation as discriminant between models Valery Andreev, UCLA

  12. Quarkonia polarization analysis α parameter: +1 – transverse polarization - 1 – longitudinal 0 – unpolarized ATLAS efficiency depends on polarisation CMS Tevatron: no model to describe cross section and polarization at the same time Valery Andreev, UCLA

  13. B-production / QCD aspects • present status of the production phenomenology at hadroncolliders • The shape of transverse momentum and angular distributions as well as the azimuthal angular correlations in a reasonable agreement with perturbativeQCD • The observed cross-sections are larger than QCD predictions • The agreement between experiment and theory has improved due to the evolution of latter mostly a consequence of improved experimental inputs • More precise parton density function, up-to-date s • Improvement on fragmentation effects estimate • The agreement is not complete, to improve the phenomenological description requires new experimental input (LHC) Review on R=σb/σNLO, F.Happaher, P.Giromini,F.Ptohos PRD 73, 014026 (2006) • experiment is • systematically • above NLO QCD • prediction Valery Andreev, UCLA

  14. B acceptance • ATLAS/CMS • || < 2.5/2.4 • Tracker/muon detector acceptance • high-Pt muon trigger • b-tagged jet trigger • LHCb • Forward spectrometer • 1.9 <  < 4.9 • much softer pt triggers CMS study: much higher Pt can be reached There is an overlap Valery Andreev, UCLA

  15. B tagging CMS PAS-BTV-07-003 (2008) • most performing: • Combined Secondary • Vertex algorithm • (high luminosity run) • different misalignment • scenarios studied • SoftMuon algorithm: • efficiency < 20 % • (B branching ratio) • robust against • misalignment Valery Andreev, UCLA

  16. CMS Analysis: Inclusive b production CMS Note 2006/120, V.P. Andreev, D.B. Cline, S. Otwinowski • B production total cross section • Differential cross sections d/dpt’ d/d • Selection • b-tagged jet • semileptonicb-decays into muons • Luminosity: 10 fb-1 • The most energetic btagged jet as • the reconstructed B-particle candidate • the rate of bjets is a direct measurement of the b production with only small fragmentation systematics Valery Andreev, UCLA

  17. Event selection • Trigger • Level-1: High Level Trigger: • “single m”, “muon + b-jet”, • pt>14 GeV/c, || < 2.1 Pt >19GeV/c, Etjet>50GeV, || < 2.4 • e = 18 %e = 60 % • Off-line selection • B-tagged jet: Et > 50 GeV, || < 2.4 • e = 65 % (barrel), 55 % (endcap) • MuonassociatedwithB-tagged jet e = 75 % Valery Andreev, UCLA

  18. B-jet resolution/B-tag efficiency Pt > 170 GeV/c B tag: inclusive secondary vertex in jets  = 12.9 %  = 5.7 % Valery Andreev, UCLA

  19. 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 Valery Andreev, UCLA

  20. b-quark Pt reach • Bhadron • Pt > 50 GeV/c • |  | < 2.4 statistical systematic We can reach 1.5 TeV as the highest measured B hadron Pt Valery Andreev, UCLA

  21. B production at LHC, PT reach Extended Pt reach • CMS analysis summary • ~16 M b events to be selected with 10 fb-1 • b purity in a range from 70 % to 55 % • up to 1.5 TeVB-hadron Pt reach Valery Andreev, UCLA

  22. Exclusive B production 10 TeV CMS PAS-BPH-09-001 (2009) Differential cross sections can be measured with statistical precision better than 10 % for 10 pb-1 luminosity (early data) B+J/ψ K+ B0J/ψ K*0 Valery Andreev, UCLA

  23. B production mechanisms at LHC PYTHIA MC prediction @ LHC hep-ph/0003142 • Both, ATLAS and CMS, will • measure bb-correlations • bbas discriminating variable bb= 465 b ( ~ 500 b ) Pair creation (LO) : ~50 b • B  J/ X + B  • bb= φJ/Ψ - φμ Gluon splitting (NLO) : ~190 b • b-jet + B  • bb= φb-jet - φμ • b-jet +b-jet • bb= φb-jet – φb-jet Flavor excitation (NLO) : ~220 b Valery Andreev, UCLA

  24. _ bb correlations B  J/ X + B   CMS PAS-BPH-08-004 (2009) • bb fraction extracted by simultaneous 3D unbinned maximum LH to • J/ψ invariant mass, J/ψ transverse flight length, μ impact parameter • Expected total uncertainty between 15 and 25 % for 50 pb-1 Valery Andreev, UCLA

  25. Conclusions • data on b production and quarkonium need to be yet reconciled with theory • ATLAS and CMS have an intense program for the QCD test in Heavy Flavor production at LHC energies • correlations and polarization measurements are foreseen to investigate in detail production mechanisms • HF measurements important for New Physics search Eagerly looking forward to the first LHC collision data this year ! Valery Andreev, UCLA