LHC Predictions Workshop, CERN, Andrea Dainese 1 R AA and R CP of single muons from heavy quark and vector boson decays at the LHC Z.Conesa del Valle 1, A.Dainese 2, H.-T.Ding 3, G.Martinez 1, D.Zhou 3 1 Subatech Nantes, 2 INFN Legnaro, 3 CCNU Wuhan Workshop on Predictions for LHC, CERN, May 29 – June 2, 2007 thanks to N.Armesto, C.Salgado, U.Wiedemann

LHC Predictions Workshop, CERN, Andrea Dainese 2 The Key Point:  ’s from W as a medium-blind reference pQCD predicts b/W crossing at p t muon ~ 30 GeV/c  from W should be unaffected by the medium b-quark energy loss would shift crossing to lower p t How would the muon R AA / R CP look like?

LHC Predictions Workshop, CERN, Andrea Dainese 3 LHC Experiments: Muon Acceptance ALICE muon spectrometer: -4 1 GeV/c CMS, ATLAS: |  | 3.5 GeV/c High p t reach in Pb-Pb: about GeV/c

LHC Predictions Workshop, CERN, Andrea Dainese 4 Baseline spectra Heavy quarks: Quark-level baseline: c and b quark single-inclusive d 2  /dp T dy from MNR code (NLO pQCD) parameters: m c =1.2 GeV,  F =  R =2m T,c, m b =4.75 GeV,  F =  R =m T,b, CTEQ4M PDFs (with EKS98 for Pb-Pb) Peterson fragmentation function (with y meson = y Q )  parameter from HERA-LHC Workshop proceedings (M.Corradi)   c =0.02,  b =0.001 (from to LEP data) Decay of meson to muon using spectator model e.g.  kinematics for B  from b  c+  +  Vector bosons: PYTHIA (reproduces W cross section at Tevatron) Cross section normalized to NLO results ( Frixione-Mangano, Vogt) more details in: Z.Conesa del Valle et al. ALICE-INT MNR code: Mangano, Nason, Ridolfi, NPB373 (1992) 295 HERA-LHC Proceedings, CERN/LHCC , hep-ph/ Frixione, Mangano, hep-ph/ ; Vogt, hep-ph/ Eskola, Kolhinen, Salgado, EPJC 9 (1999) 61

LHC Predictions Workshop, CERN, Andrea Dainese 5 Total single-muon spectrum in Pb-Pb without E loss ALICE muon spectrometer acc.: -4 1 GeV, p > 4 GeV

LHC Predictions Workshop, CERN, Andrea Dainese 6 Effect of shadowing (EKS98) in Pb-Pb W beauty charm total -4 <  < -2.5

LHC Predictions Workshop, CERN, Andrea Dainese 7 Effect of shadowing (EKS98) in Pb-Pb W beauty charm total just an indication (PYTHIA LO): -4 <  < -2.5

LHC Predictions Workshop, CERN, Andrea Dainese 8 Effect of shadowing (EKS98) in Pb-Pb val. q sea q gluon EKS98 val. q EKS98 sea q W 1.0*0.85=0.85 W beauty charm total ALICE muon spectrometer -4 <  < -2.5

LHC Predictions Workshop, CERN, Andrea Dainese 9 Effect of shadowing (EKS98) in Pb-Pb val. q sea q gluon b EKS98 gluon 0.95*1.05=1 W beauty charm total ALICE muon spectrometer -4 <  < -2.5

LHC Predictions Workshop, CERN, Andrea Dainese 10 Heavy Quark Radiative E Loss Mass-dependent BDMPS quenching weights Glauber collision geometry à la PQM Transport coefficient for a static medium: Armesto, Dainese, Salgado, Wiedemann, PRD 71 (2005) EKRT Saturation model Eskola, Kajantie, Ruuskanen, Tuominen, NPB 570 (2000) 379.  C.Salgado  C.Loizides (corresponds to dN ch /dy ~ 3000)

LHC Predictions Workshop, CERN, Andrea Dainese 11 E loss for c and b VS rapidity Calculation of radiated energy: compute  E using L t ; quench p t ; 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/ (gives moderate density change for |  | < 4) ptpt y LtLt -15% negligible effect on muon suppression for |  | < 4

LHC Predictions Workshop, CERN, Andrea Dainese 12 Effect of E loss in Pb-Pb 0-10% Crossing point shifts down by 5-7 GeV/c R AA increases from 0.3 to 0.8 R CP (0-10%)/(40-70%) increases from 0.4 to 0.9 Similar results in -4 <  < -2.5

LHC Predictions Workshop, CERN, Andrea Dainese 13 Effect of E loss in Pb-Pb 0-10% - b mass effect - thin: no mass effect thick: mass effect thin: no mass effect thick: mass effect R AA R CP

LHC Predictions Workshop, CERN, Andrea Dainese 14 Summary At LHC, high p t muon spectrum will be one of the first measurements sensitive to b quark energy loss Crossing point of b and W muons shifts down by 5-7 GeV/c R AA rapidly increases from 0.3 to 0.8 between 20 (b- dominated) and 40 GeV/c (W-dominated)

LHC Predictions Workshop, CERN, Andrea Dainese 15 EXTRA SLIDES

LHC Predictions Workshop, CERN, Andrea Dainese 16 Baseline:  from c and b, no E loss (from Z.Conesa) B  D  can be neglected: MNR+Peterson+spectator model decay VS PYTHIA (ALICE tune)

LHC Predictions Workshop, CERN, Andrea Dainese 17  from b with E loss: effect of mass Effect of b-quark mass for p t muon < GeV/c

LHC Predictions Workshop, CERN, Andrea Dainese 18  from b with E loss: effect of dN/d  scaling for qhat In this model, the effect of density decrease at forward y is negligible within the MUON spectrometer acceptance

LHC Predictions Workshop, CERN, Andrea Dainese 19 Effect of E loss in Pb-Pb - ALICE muon spectrometer -

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