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Effect of heavy-quark E loss on the single m p t distribution

Effect of heavy-quark E loss on the single m p t distribution. Heavy-quark energy loss, from RHIC to LHC Energy loss at forward rapidity (ALICE MUON arm) R AA of single muons (c+b+W/Z), without and with E loss. Andrea Dainese with Z.Conesa del Valle, H.Ding, G.Martinez, D.Zhou.

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Effect of heavy-quark E loss on the single m p t distribution

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  1. Effect of heavy-quark E loss on the single m pt distribution • Heavy-quark energy loss, from RHIC to LHC • Energy loss at forward rapidity (ALICE MUON arm) • RAA of single muons (c+b+W/Z), without and with E loss Andrea Dainese with Z.Conesa del Valle, H.Ding, G.Martinez, D.Zhou ALICE Physics Week, Muenster, 15.02.2007 Andrea Dainese

  2. The Key Point:m’s from W as a medium-blind reference • pQCD predicts b/W crossing at ptmuon ~ 30 GeV/c • In Pb-Pb, b-quark in-medium energy loss would shift crossing to lower pt • How would the muon RAA look like? Z.Conesa del Valle, G.Martinez, L. Aphecetche and Ch. Finck, ALICE-INT-2006-021 ALICE Physics Week, Muenster, 15.02.2007 Andrea Dainese

  3. path length L Gluonsstrahlung probability w Q kT l in medium, dead cone implies lower energy loss Heavy Quark Radiative Energy Loss ➔ N.Armesto (BDMPS) Energy loss depends on: colour coupling factor: 4/3 for q, 3 for g medium transport coefficient “Dead cone” effect for heavy quarks: in vacuum, gluon radiation suppressed at q < mQ/EQ Baier, Dokshitzer, Mueller, Peigne‘, Schiff, NPB 483 (1997) 291. Salgado, Wiedemann, PRD 68(2003) 014008. Dokshitzer and Kharzeev, PLB 519 (2001) 199. Armesto, Salgado, Wiedemann, PRD 69 (2004) 114003. ALICE Physics Week, Muenster, 15.02.2007 Andrea Dainese

  4. Reference for density: p0 RAA at RHIC QM06 (PHENIX highlights) ALICE Physics Week, Muenster, 15.02.2007 Andrea Dainese

  5. nucl-ex/0611018 QM06 update RAA of c and b electrons at RHIC ➔ F.Antinori b c+b c Radiative E loss calculations tend to underpredict suppression Armesto, Cacciari, Dainese, Salgado, Wiedemann, PLB637 (06) 326, Djordjevic, Gyulassy, Wicks, nucl-th/0512076 ALICE Physics Week, Muenster, 15.02.2007 Andrea Dainese

  6. Heavy Flavour RAA at LHC (y = 0) • y~0 (in-medium path and E loss in transverse plane) • Baseline: PYTHIA, with EKS98 shadowing, tuned to reproduce c and b pT distributions from NLO pQCD (MNR) • (m/E)-dep. E loss with • * EKRT Saturation model: Eskola, Kajantie, Ruuskanen, Tuominen, NPB 570 (2000) 379. Armesto, Dainese, Salgado, Wiedemann, PRD 71 (2005) 054027. MNR: Mangano, Nason, Ridolfi, NPB 373 (1992) 295. ALICE Physics Week, Muenster, 15.02.2007 Andrea Dainese

  7. Beauty in ALICE via forward muons • Muons identified in the ALICE forward spectrometer (MUON acceptance: -4 << -2.5, p > 4 GeV/c, pt > 1 GeV/c)  single muons in the spectrometer: beauty dominates for pt > 2-3 GeV/c inner bars: stat. errors outer bars: syst. errors Pb-Pb 0-5% R.Guernane et al. in PPR2 ALICE Physics Week, Muenster, 15.02.2007 Andrea Dainese

  8. E loss simulation: Baseline spectra Modified procedure for QMQm kinematics (for faster calculations): • Quark-level baseline: c and b quark single-inclusive d2s/dptdy from MNR code (NLO pQCD) • same parameters as for the PPR: mc=1.2 GeV, mF=mR=2mt,c, mb=4.75 GeV, mF=mR=mt,b, CTEQ4M PDFs (with EKS98 for Pb-Pb) • Peterson fragmentation function (with ymeson = yQ) • e parameter from HERA-LHC Workshop proceedings (M.Corradi) • ec=0.02, eb=0.001 (from to LEP data) • Decay of meson to muon using spectator model • e.g. m kinematics for Bm from bc+m+nm MNR code: Mangano, Nason, Ridolfi, NPB373 (1992) 295 Eskola, Kolhinen, Salgado, EPJC 9 (1999) 61 HERA-LHC Proceedings, CERN/LHCC 2005-014, hep-ph/0601164 ALICE Physics Week, Muenster, 15.02.2007 Andrea Dainese

  9. BDm can be neglected: Baseline: m from c and b, no E loss MNR+Peterson+spectator model decay VS PYTHIA (ALICE tune) (from Z.Conesa) (from Z.Conesa) ALICE Physics Week, Muenster, 15.02.2007 Andrea Dainese

  10. Total single-muon spectrum in Pb-Pb Z.Conesa del Valle, G.Martinez, L. Aphecetche and Ch. Finck, ALICE-INT-2006-021 ALICE Physics Week, Muenster, 15.02.2007 Andrea Dainese

  11. Effect of shadowing (EKS98) in Pb-Pb (from Z.Conesa) (from Z.Conesa) ALICE Physics Week, Muenster, 15.02.2007 Andrea Dainese

  12. Effect of shadowing (EKS98) in Pb-Pb W beauty charm total ALICE Physics Week, Muenster, 15.02.2007 Andrea Dainese

  13. Effect of shadowing (EKS98) in Pb-Pb just an indication (PYTHIA LO): W beauty charm total ALICE Physics Week, Muenster, 15.02.2007 Andrea Dainese

  14. Effect of shadowing (EKS98) in Pb-Pb val. q sea q gluon gluon W beauty charm total W 1.0*0.85=0.85 EKS98 sea q EKS98 val. q ALICE Physics Week, Muenster, 15.02.2007 Andrea Dainese

  15. EKS98 gluon EKS98 gluon Effect of shadowing (EKS98) in Pb-Pb val. q sea q gluon gluon W beauty charm total b 0.95*1.05=1 ALICE Physics Week, Muenster, 15.02.2007 Andrea Dainese

  16. Q pt p L Lt -15% pz E loss for c and b VS rapidity Calculation of radiated energy: compute DE using Lt; quench pt; keep y constant. • Decrease of medium density at forward rapidity should be accounted for • Assumed , i.e. • using LHC multiplicity as predicted by D.Kharzeev, E.Levin, M.Nardi, hep-ph/0408050 (gives moderate density change for |h| < 4) ALICE Physics Week, Muenster, 15.02.2007 Andrea Dainese

  17. m from b with E loss:effect of mass Effect of b-quark mass for ptmuon < 20-30 GeV/c ALICE Physics Week, Muenster, 15.02.2007 Andrea Dainese

  18. m from b with E loss:effect of dN/dh scaling for qhat In this model, the effect of density decrease at forward y is negligible within the MUON spectrometer acceptance ALICE Physics Week, Muenster, 15.02.2007 Andrea Dainese

  19. Effect of E loss in Pb-Pb RAA increases from 0.3 to 0.8 Crossing point shifts down by 5-7 GeV/c ALICE Physics Week, Muenster, 15.02.2007 Andrea Dainese

  20. Effect of E loss in Pb-PbMUON acceptance ALICE Physics Week, Muenster, 15.02.2007 Andrea Dainese

  21. Effect of E loss in Pb-Pb thin: no mass effect thick: mass effect ALICE Physics Week, Muenster, 15.02.2007 Andrea Dainese

  22. Conclusions • First estimation of energy loss effect on high pt muons • Crossing point of b and W muons shifts down by 5-7 GeV/c • RAA rapidly increases from 0.3 to 0.8 between 20 (b-dominated) and 40 GeV/c (W-dominated) • RCP (0-10%)/(40-70%) • Expected ALICE sensitivity to RAA and RCP (pt coverage) Outlook ALICE Physics Week, Muenster, 15.02.2007 Andrea Dainese

  23. Guten Appetit! ALICE Physics Week, Muenster, 15.02.2007 Andrea Dainese

  24. EXTRA SLIDES ALICE Physics Week, Muenster, 15.02.2007 Andrea Dainese

  25. ALICE Physics Week, Muenster, 15.02.2007 Andrea Dainese

  26. ALICE Physics Week, Muenster, 15.02.2007 Andrea Dainese

  27. ALICE Physics Week, Muenster, 15.02.2007 Andrea Dainese

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