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Heavy flavor physics with the EMCal in ALICE

Heavy flavor physics with the EMCal in ALICE. J.L. Klay, LLNL 06-Oct-2006. Heavy flavor topics. …with electrons. Cross-sections/baseline for exploring other effects. Heavy flavor production Inclusive electrons/R AA Electron-hadron correlations Electron-tagged jets Electron v2 Di-leptons

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Heavy flavor physics with the EMCal in ALICE

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  1. Heavy flavor physics with the EMCal in ALICE J.L. Klay, LLNL 06-Oct-2006

  2. Heavy flavor topics …with electrons Cross-sections/baseline for exploring other effects Heavy flavor production Inclusive electrons/RAA Electron-hadron correlations Electron-tagged jets Electron v2 Di-leptons …? Medium effects/ Heavy Quark Energy loss Bulk properties/thermalization Color screening/ Quarkonia melting How do we use the EMCal to explore this physics?

  3. Why Electrons? Tag heavy quark mesons through semi-leptonic decays BR(D±,0e) = 17.2,6.8% BR(B±,0e) = 10.2,10.3% BR(BDe) = 9.6% EMCal provides good electron PID and high pT trigger

  4. Expectations NLO predictions (ALICE baseline for charm & beauty) In pp, important test of pQCD in a new energy domain remember the “15-years saga of b production at the Tevatron”*… …and c production not yet fully reconciled factor ~2 uncertainty (more later) MNR code (NLO): Mangano, Nason, Ridolfi, NPB373 (1992) 295. CDF, PRL91 (2003) 241804 FONLL: Cacciari, Nason Cacciari, Frixione, Mangano, Nason and Ridolfi, JHEP0407 (2004) 033 M.Cacciari * M.Mangano A. Dainese, HP2006

  5. Total cross-sections from RHIC STAR PHENIX

  6. Comparing theory/experiment PHENIX How well do we understand our baseline? How good are predictions for LHC?

  7. Uncertainties CERN/LHCC 2005-014, hep-ph/0601164 NLO pQCD, pp, s = 14 TeV MNR code: Mangano, Nason, Ridolfi, NPB373 (1992) 295. A. Dainese, HP2006

  8. Heavy Quark Energy Loss U. Wiedemann, SQM2006

  9. GLV calculations (1st order opacity expansion) RHIC, dNg/dy=1000 LHC, dNg/dy=3000 M. Djordjevic, HP2006

  10. Electron RAA at RHIC PHENIX STAR radiative only (c+b)→e (1)-(3), N Armesto, et al. PRD 71, 054027 Bands, S. Wicks, et al. nucl-th/0512076 radiative + collisional (c+b)→e radiative + collisional c→e A. Dion and P. Djawotho, HP2006

  11. How important is Collisional E-loss? Early work: Recent work: E. Braaten and M. H. Thoma, Phys. Rev. D 44, 2625 (1991). M. H. Thoma and M. Gyulassy, Nucl. Phys. B 351, 491 (1991). Collisional energy loss is negligible! Conclusion was based on inaccurate assumptions (i.e. they used α=0.2), and assumed that dE/dL<0.5 GeV/fm is negligible. Collisional and radiative energy losses are comparable! M.G.Mustafa,Phys.Rev.C72:014905,2005 A. K. Dutt-Mazumder et al.,Phys.Rev.D71:094016,2005 Above computations are done in an ideal infinite QCD medium. Will collisional energy loss still be important once finite size effects are included? M. Djordjevic, HP2006

  12. Collisional vs. radiative Collisional and radiative energy losses are comparable! M.Djordjevic, nucl-th/0603066 M. Djordjevic, HP2006

  13. Heavy/Light Ratios U. Wiedemann, SQM2006

  14. LHC predictions U. Wiedemann, SQM2006

  15. Bottom/Charm Ratios Compare c and b: same colour charge Mass effect  Enhancement of factor ~2, independent of (for ) Adapted from Armesto, Dainese, Salgado, Wiedemann, PRD71 (2005) 054027 A. Dainese, HP2006

  16. Heavy quark jet identification e D n B b b • Look for jets with leading high pT electrons • Electron-hadron correlations

  17. Results from the Tevatron Collider experiments use b-jets to look for Higgs, electrons to tag b-jets CDF, Phys. Rev. D69 (2004) 072004 hep-ex/0311051 p+p, 1.8 TeV Herwig Simulation: bb di-jets within |η|<1.5 Event selection: (69K e + 15K μ) - di-jet with ETuncorr>15 GeV (<ETparton> ~ 20 GeV) - pT>8 GeV lepton within ΔR < 0.4 - Correction for fake tags Good agreement between simulation and data JLK, SQM2004

  18. Electron-hadron correlations Photonic Backgrounds: 0, Dalitz decay electrons 0, * e+e-Conversion photons 0,   e+e- PYTHIA 6.152 CTEQ5L, MSEL = 1 ETmin = 2 GeV (70M events sampled to get 100k events with e pT>1GeV/c,|| < 0.35) e: 1 < pTtrig < 4 GeV/c h: 1 < pTassoc < 4 GeV/c Photonic/Non-photonic contributions have similar shape, different widths JLK, DNP05

  19. PHENIX Results in p+p/d+Au RNP• Photonic e-h Non-photonic e-h Inclusive e-h Run 2 p+p PHENIX Preliminary PHENIX Preliminary PHENIX Preliminary Run 3 d+Au PHENIX Preliminary PHENIX Preliminary PHENIX Preliminary Systematic uncertainty e: 2<pTtrig<3GeV/c h: 1<pTassoc<4GeV/c Jet-like structure in p+p and d+Au JLK, DNP05

  20. ATLAS jet-tagging studies u rejection b efficiency • Rejection factor against light-quark jets vs b-tagging eff. • Based only on impact parameter selection • Central Pb-Pb (HIJING) • Factor 50 rejection when efficiency 40% required What can ALICE+EMCal do?

  21. Electron v2 f = p/2 f = 0 • Azimuthal asymmetry --v2 or RAA(f)-- of D and B mesons in non-central collisions tests: • at low/moderate pt: recombination scenario, flow of c/b quarks (?), hence degree of thermalization of medium • at higher pt: path-length dependence of E loss in almond-shaped medium A. Dainese, HP2006

  22. Color screening/Dissociation Suppression Models: –Heavy quarkonia are formed only during the initial hard nucleon-nucleon collisions –Subsequent interactions only result in additional loss of yield Color Screening: –Color charge of one quark masked by the surrounding quarks –Prevents cc-bar binding in the interaction region –Characterized by the Debye screening radius (rD) –If the screening radius is smaller than the J/ radius then the quarks are effectively masked from one another Melting of bound states as plasma temperature increases

  23. The view at RHIC J/ total cross-section in p+p vs rapidity Models require both suppression and regeneration to explain data RAA for J/ for all systems, mid(ee) and forward() rapidities

  24. Quarkonia J/(cc) enhanced regeneration enhanced suppression Statistical hadronization: huge enhancements for Xcc, Wcc, Bc, Wccc e.g. 1000 for Wccc/Dfrom pp to Pb-Pb 30 SPS RHIC LHC Becattini, PRL95 (05) 022301  H.Satz • J/ suppression & regeneration? • c, y’ suppression (J/ TD ~ 1.5-2 Tc)? Satz, CERN Heavy Ion Forum, 09/06/05 • TLHC >> J/ TD • Wong, PRC 72 (2005) 034906 • Alberico, hep-ph/0507084 A. Dainese, HP2006

  25. Quarkonia Y(bb) RHIC LHC Gunion and Vogt, NPB 492 (1997) 301  production ’/ vs pt sensitive to system temp. & size Vogt, hep-ph/0205330  ds/dy @ LHC ~20 x RHIC H.Satz •  melts only at LHC • ’ TD ~ J/ TD • Wong, PRC 72 (2005) 034906 • Alberico, hep-ph/0507084 • Small  regeneration • Grandchamp et al., hep-ph/0507314 • ’ can unravel J/ suppression vs. regeneration A. Dainese, HP2006

  26. ALICE Capabilities DpT/pT Central Pb+Pb p+p Robust, redundant tracking: 100 MeV/c to 100 GeV/c ITS (Silicon): 4<r<44 cm, 6 layers TPC: 85<r<245 cm, 159 pad rows TRD: 290<r<370 cm, 6 layers B field = 0.5 T  good pattern recognition Long lever arm  good momentum resolution Small material budget: vertexTPC outer field cage < 0.1 X0 107 Central Pb+Pb events  p K TPC dE/dx ~5.5-6.5% ALICE PPR CERN/LHCC 2003-049

  27. Tracking/Secondary vertices • D mesons ct ~ 100–300 mm, B mesons ct ~ 500 mm • Secondary vertex capabilities! Impact param. resolution! ALICE ITS + TPC + TRD B = 0.5 T Dpt/pt < 2.5% up to 20 GeV/c < 3% up to 100 GeV/c acceptance: pt > 0.2 GeV/c rf < 50 mm for pt > 1.5 GeV/c

  28. ALICE Electron ID Combined info from TRD (trans. rad.) and TPC (dE/dx) TRD rejects 99% of the p and ALL heavier hadrons (pt > 1 GeV/c) TPC further rejects residual pions (up to 99% at low p) About 20% of electrons rejected fraction of misidentified pions How does EMCal help? A. Dainese, HP2006

  29. Preliminary EMCAL Studies e h E/p Combine information from TRD/EMCAL for e PID B/D decay vertex reconstruction with ITS • GEANT, all material • E/p from EMCal/tracking; shower-shape 103 1/pion efficiency 20 GeV electron efficiency • First look: good hadron rejection at 20 GeV • Not yet addressed: electron backgrounds

  30. Beauty via electrons electron rec. track e Primary Vertex B X d0 1 year at nominal luminosity (107 central Pb-Pb events, 109 pp events) B  e + X What improvements can EMCal provide?

  31. ALICE Heavy/light ratios B  e + X mb = 4.8 GeV 1 year at nominal luminosity (107 central Pb-Pb events, 109 pp events) ALICE will also measure RDAA via D->K How can EMCal improve/extend this measurement? A. Dainese, HP2006

  32. ALICE Onia with electrons J/yee 245, -- J/y, y’ 21, 8, -- ,’,’’ ee J/y e+e- ALICE: CERN/LHCC 99-13

  33. ALICE Material budget Important for understanding conversion electron backgrounds Critical lesson from RHIC: Need to verify simulation reflects reality/ Understand material details

  34. Making a good thing better   We need to show this! With ALICE tracking, TPC+TRD PID, and secondary vertex reconstruction in ITS, heavy flavor with electrons in ALICE is already very good. • What does the EMCal bring to the table? • Triggering (e.g. high pT electrons) • Improved Jet reconstruction (jet-tagging) • Extended electron pT reach, PID

  35. Heavy flavor physics timeline Many heavy flavor observables can be studied with small coverage (albeit with limited statistics) -- advance preparation for jet-tagging and full coverage analysis See my talk tomorrow for status of offline software and how to get involved!

  36. Backup

  37. Kinematic reach of ALICE+EMCal • 104/year for Minbias Pb+Pb: • Inclusive jets: ET>200 GeV • Di-jets: ET>170 GeV • Inclusive 0: pT~75 GeV • Inclusive : pT~45 GeV • Inclusive e: pT~25 GeV

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