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Charm and Beauty at LHC (open flavour and quarkonia)

HARD PROBES 2006 Asilomar, CA, June 9-16, 2006. Charm and Beauty at LHC (open flavour and quarkonia). Andrea Dainese INFN – Legnaro. Contents. Heavy flavour & Quarkonia at LHC: WHY? Heavy flavour & Quarkonia at LHC: HOW? ALICE, ATLAS, CMS

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Charm and Beauty at LHC (open flavour and quarkonia)

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  1. HARD PROBES 2006 Asilomar, CA, June 9-16, 2006 Charm and Beauty at LHC(open flavour and quarkonia) Andrea Dainese INFN – Legnaro Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  2. Contents • Heavy flavour & Quarkonia at LHC: WHY? • Heavy flavour & Quarkonia at LHC: HOW? ALICE, ATLAS, CMS • Selected examples of the physics potential for open heavy-flavour & quarkonia thanks to: A. Morsch, P. Crochet, F. Antinori, B. Wyslouch, G. Roland, D. d’Enterria, H. Takai Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  3. OPEN HEAVY FLAVOUR Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  4. factor ~2 uncertainty (more later) large LHC: hard cross sectionslots of heavy quarks! • 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 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 Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  5. Theoretical Uncertainties CERN/LHCC 2005-014, hep-ph/0601164 NLO pQCD, pp, s = 14 TeV charm beauty MNR code: Mangano, Nason, Ridolfi, NPB373 (1992) 295. Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  6. Energy extrapolation via pQCD? • Different systems (pp, p-Pb, Pb-Pb) will have different s values • Results in pp at 14 TeV will have to extrapolated to 5.5 TeV (Pb-Pb energy) to compute, e.g., nuclear modification factors RAA • pQCD: ratio of cross sections at 14 TeV/5.5 TeV has small uncertainty charm beauty 12% 8% FO NLO (MNR) [to be repeated with FONLL] Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  7. increasing s LHC: small-x • Probe unexplored small-x region with HQs at low pt and/or forward y • down to x~10-4 with charm already at y=0 • Window on the rich phenomenology of high-density PDFs: gluon saturation / recombination effects / CGC Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  8. path length L Gluonsstrahlung probability w Q kT l in medium, dead cone implies lower energy loss Heavy Quark Energy Loss  C.Salgado (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. Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  9. News from RHIC: heavy-flv decay electrons suppressed! Indirect measurement: non-g electrons (Dalitz and conversions subtracted); c / b inclusive (large uncertainty on pp baseline!!)  C.Salgado  M.Djordjevic Radiative Radiative + Collisional Energy loss calculations tend to underpredict suppression Djordjevic, Gyulassy, Wicks, nucl-th/0512076 Armesto, Cacciari, Dainese, Salgado, Wiedemann, PLB637 (06) 326. Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  10. f = p/2 f = 0 Armesto, Cacciari, Dainese, Salgado, Wiedemann, PLB637 (06) 326. Azimuthal asymmetry (v2) • 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 PHENIX p0 v2 Cole @ Quark Matter 05 v2 from E loss: Dainese, Loizides, Paic, EPJC 38 (2005) 461 Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  11. mass effect LHC: colour-charge and mass dep. of E loss with Heavy-to-Light ratios Heavy-to-light ratios: Compare g  h , c  D and b  B  C.Salgado For 10 < pt < 20 GeV/c, charm behaves like a m=0 quark, light-flv hadrons come mainly from gluons RD/h enhancement probes colour-charge dep. of E loss RB/h enhancement probes mass dep. of E loss Armesto, Dainese, Salgado, Wiedemann, PRD71 (2005) 054027 Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  12. LHC: Beauty-to-Charm ratio RB/D • 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 Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  13. CMS ATLAS Experimental study of heavy flavours in AA at the LHC Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  14. acceptance: pt > 0.2 GeV/c rf < 50 mm for pt > 1.5 GeV/c acceptance: pt > 1 GeV/c rf < 50 mm for pt > 2.5 GeV/c B = 0.5 T B = 4 T Dpt/pt < 2% up to 100 GeV/c Dpt/pt < 2.5% up to 20 GeV/c < 3% up to 100 GeV/c Tracking & Vertexing • D mesons ct ~ 100–300 mm, B mesons ct ~ 500 mm • Secondary vertex capabilities! Impact param. resolution! Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  15. Lepton and Hadron ID • D and B: large B.R. to leptons: ~10% e + ~10% m • ALICE: • electrons: Transition Rad. + dE/dx in |h| < 0.9 and pt > 1 GeV/c + EM cal (performance under study) • muons: -4 <h< -2.5 and pt >1 GeV/c (use pz to punch through abs.) • CMS (ATLAS): • muons: |h| < 2.4 (3) and pt > 3.5 (4) GeV/c • electrons in EM cal? (no heavy-ion studies yet) • With leptons, difficult to measure D(B) pt distr. and go to low pt (loose pt correlation) Exclusive hadronic decay channels (charm)  Need PID (kaons!) to reject huge combin. background in AA • ALICE hadron ID: large TPC + high-res TOF + RICH (small acc.) Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  16. Invariant mass analysis Charm reconstruction: D0 K-p+ • Large combinatorial background (dNch/dy=6000 in central Pb-Pb!) • Main selection: displaced-vertex selection • pair of opposite-charge tracks with large impact parameters • good pointing of reconstructed D0 momentum to the primary vertex Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  17. rec. track e Primary Vertex B X d0 Beauty via displaced electrons • ALICE has excellent electron identification capabilities • Displaced electrons from B decays can be tagged by an impact parameter cut Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  18. electron CMS & ATLAS • should have similar performance, • at least with muons • higher ptmin because more material • & larger field • should have similar performance • higher ptmin because lack of K id Expected pt coverage 1 year at nominal luminosity (107 central Pb-Pb events, 109 pp events) D0 Kp B  e + X Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  19. mb = 4.8 GeV Low pt (< 6–7 GeV/c) Also nuclear shadowing (here EKS98), in-medium hadr… High pt (> 6–7 GeV/c) Only parton energy loss Charm and Beauty E Loss : RAA D0 Kp B  e + X 1 year at nominal luminosity (107 central Pb-Pb events, 109 pp events) Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  20. Heavy-to-light ratios in ALICE 1 year at nominal luminosity (107 central Pb-Pb events, 109 pp events) Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  21. W (weakly interacting) dominates for pt > 30 GeV/c!! Beauty via (forward) muons • Muons “identified” in the forward spectrometer (-4 << -2.5)  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% Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  22. u rejection b efficiency ATLAS: b-tagged Jets • Based only on impact parameter selection • Central Pb-Pb (HIJING) events • Rejection factor against light-quark jets vs b-tagging eff. • Factor 50 rejection when efficiency 40% required • Should improve when combined with m tagging Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  23. QUARKONIA Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  24. 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 Quarkonia at LHC: y (cc)  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 Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  25. RHIC LHC Gunion and Vogt, NPB 492 (1997) 301  production ’/ vs pt sensitive to system temp. & size Vogt, hep-ph/0205330 Quarkonia at LHC:  (bb)  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 Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  26. Quarkonia at LHC:experimental challenges • Important contribution to y production from B J/y(y’) + X • ~20% of J/y • ~40% of y’ • Normalization: Drell-Yan not available for normalization (from qq, while quarkonia from gg at LHC; and small cross section at LHC)  W, Z? • Different Q2, x Open heavy flavour, but … • Energy loss? • Thermal charm production?  Possible alternative: RAA (à la PHENIX) Need to measure this! Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  27. m+m- m+m- m+m- e+e- J/y  J/y  acceptance (%) -4<h<-2.5 -4<h<-2.5 Quarkonia acceptances Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  28. Charmonia Performance Bkg input: dNch/dy~2500-4000 in central Pb-Pb. for 1 month central central min. bias central Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  29. Bottonia Performance Bkg input: dNch/dy~2500-4000 in central Pb-Pb. for 1 month central central min. bias central |h|<0.8 |h|<2.4 Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  30. primary J/y J/y from B J/y from B in CMS & ALICE J/ym+m- J/y e+e- CMS: CMS/NOTE 2001/008,ALICE: CERN/LHCC 99-13 Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  31. 442 days to LHC startup! Summary • The LHC will be a heavy-quarks and quarkonia factory • Heavy quarks as probes of QCD in extreme conditions • from low pt: probe small-x structure of p and nucleus • to high pt: probe the medium via energy loss • Charmonia and Bottonia as probes of QCD phase transition • Excellent “heavy-quark busters” (ALICE, ATLAS, CMS) are being installed at CERN Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  32. EXTRA SLIDES Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  33. LHC running conditions pp nominal run Pb-PB nominal run Ldt dt = 3.1030 cm-2 s-1 x 107 s 5.1037 cm-2 for pp run, 14 TeV Npp collisions = 2 .1012 collisions Ldt = 5.1026 cm-2 s-1 x 106 s 5.1032 cm-2 PbPb run, 5.5 TeV NPbPb collisions = 2 .109 collisions   Muon triggers: ~ 100% efficiency, < 1kHz Muon triggers: ~ 100% efficiency, ~ 1kHz Electron triggers: ~ 50% efficiency of TRD L1 20 physics events per event Electron triggers: Bandwidth limitation NPbPb central = 2 .108 collisions Hadron triggers: Npp minb = 2 .109 collisions Hadron triggers: NPbPb central = 2 .107 collisions   Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  34. Probing nuclear PDFs with HQs • Shadowing in pA (AA) • CGC in pA (AA) • Double parton scattering in pA Eskola, Kolhinen, Salgado, EPJC 9 (1999) 61 Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  35. Probing nuclear PDFs with HQs • Shadowing in pA (AA) • CGC in pA (AA) • Double parton scattering in pA • Saturation scale Qs2(x) ~ xg(x)A/RA2 ~ xg(x)A1/3 • At LHC for x~10-4, Qs~1.5-2 GeV > mc • For mt,c~Qs, charm prod. CGC-dominated: • scales with Npart in pA (not Ncoll) • harder pt spectra, since typical kt~Qs~1.5 GeV, while • in standard factorization kt~LQCD~0.2 GeV Kharzeev, Tuchin, NPA 735 (2004) 248 Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  36. predicted rate: cccc/cc ~ 10% (Treleani et al.) signature: events with “tagged” DD (can use D0+e+ or e+e+) and ch. conj. NB: there is a “background” from normal bb events, but is can be estimated from measured single inclusive b cross section Probing nuclear PDFs with HQs • Shadowing in pA (AA) • CGC in pA (AA) • Double parton scattering in pA probe “many-body” PDFs normal and anomalous: different A dep. Cattaruzza, Del Fabbro, Treleani, PRD 70 (2004) 034022 Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  37. Heavy Flavour RAA at LHC • 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. Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  38. ALICE pT [GeV/c] Tracking efficiency, fakes ATLAS CMS CMS (dN/dy ~ 3500) (dN/dy ~ 3500) Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  39. fraction of misidentified pions Electron identification • 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 Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  40. measured at 14 TeV, then scaled by pQCD to 5.5 TeV Calibrating the probe (pp, s = 14 TeV) Expected sensitivity in comparison to pQCD: B  e + X D0 Kp 1 year at nominal luminosity (109 pp events) Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  41. 1 year at nominal luminosity ~1 month at end 2007 pp: perspectives for the 1st month • When? Latest statement from the machine (June 7): “Machine Closure: 31.8.07 Set up of machine, injection, followed by up to 10 weeks of pp collisions: Sept. to Dec. 2007” • Expected statistical errors for a low-stats sample: • Scaling of statistical errors according to Nevts • No dedicated cuts study yet D0 Kp B  e + X Detector configuration: ITS + TPC + TOF Detector configuration: ITS + TPC + TRD Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  42. 3-body decays: D+ and Ds+ • D+: complementary to D0 measurement, important systematic check • D+ (ct ~ 310 mm) → Kpp with BR ~ 9.2% compared to • D0 (ct ~ 124 mm) → Kp with BR ~ 3.8% better separation and higher BR, but worse comb. background • preliminary studies: similar performance as for D0expected • Ds+: probe of hadronization? • from fragmentation (PYTHIA): Ds+(cs) / D+(cd) ~ 0.6 • from stat. hadronization: Ds+/D+ ~ gs / gq ~ 1 in QGP? • Ds+ (ct ~ 150 mm) → KKp with BR ~ 4.4 % worse conditions than D+, but large resonant fraction in decay (through fp or K0*K+) will help in comb. background rejection Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  43. 0 < b < 3 fm 0 < b < 3 fm 0 < b < 3 fm 1. 2. 3. Extracting quarkonia signals • Example (bottonia to di-muon in ALICE): • get invariant mass cocktail for all centrality & pt bins • subtract non-correlated dimuons (event-mixing subtraction) • fit invariant mass spectra with 3 modified Landau convoluted with Gaussian & exponential for background Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

  44. Suppression scenario in ALICE • Suppression-1 • Tc =270 MeV • TD/Tc=1.7 for J/Y • TD/Tc= 4.0 for . • Suppression-2 • Tc=190 MeV • TD/Tc=1.21 for J/Y • TD/Tc= 2.9 for . PRC72 034906(2005) Hep-ph/0507084(2005) Good sensitivity J/y,  & ’ Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese

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