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Heavy-flavour quenching studies with ALICE

1 st ALICE Physics Week. Heavy-flavour quenching studies with ALICE. Andrea Dainese Padova – Universit à e INFN. Contents. Introduction Why? (see Carlos’ talk) Which observables? Possibilities with ALICE (landscape of channels) here, focus on D 0  K p and B  e +X

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Heavy-flavour quenching studies with ALICE

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  1. 1st ALICE Physics Week Heavy-flavour quenching studies with ALICE Andrea Dainese Padova – Università e INFN ALICE Physics Week - Erice, 06.12.2005 Andrea Dainese

  2. Contents • Introduction • Why? (see Carlos’ talk) • Which observables? • Possibilities with ALICE (landscape of channels) • here, focus on D0 Kp and B  e+X • Nuclear modification factors • pp, the importance of the baseline • expected uncertainties and coverage in pt • Understanding RAA • the role of the initial state • the role of hadronisation ALICE Physics Week - Erice, 06.12.2005 Andrea Dainese

  3. 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. MNR: Mangano, Nason, Ridolfi, NPB 373 (1992) 295. ALICE Physics Week - Erice, 06.12.2005 Andrea Dainese

  4. mass effect RD/h enhancement probes color-charge dep. of E loss RB/h enhancement probes mass dep. of E loss Color-charge and mass dep. of E loss with Heavy-to-Light ratios at LHC Heavy-to-light ratios: Compare g  h , c  D and b  B Armesto, Dainese, Salgado, Wiedemann, PRD71 (2005) 054027 ALICE Physics Week - Erice, 06.12.2005 Andrea Dainese

  5. How in ALICE (non-exaustive list) • Charm mesons at central rapidity y (D0 Kp, D+ Kpp …) • A.D., E.Bruna • Electrons from beauty at central y • R.Turrisi, C.Bombonati • Muons from beauty at forward y • R.Guernane • Muons from W at forward y • Z.Conesa del Valle RAA and RD/h RAA (and RB/h?) RAA RAA at W/b m crossing in pt ALICE Physics Week - Erice, 06.12.2005 Andrea Dainese

  6. PHENIX preliminary data (QM) vs FONLL uncertainty band Role of pp reference for RAA(at RHIC) • Exclusive measurements at same energy in AA and pp (e.g. p0 at 200 GeV) • experimental reference sufficient for solid observation of high-pt quenching • not sufficient for interpretation in terms of parton energy loss theoretically-understood reference needed • Inclusive measurement at same energy in AA and pp (e.g. c+b electrons at 200 GeV) theoretically-understood reference needed also for observation (see Carlos’ talk) ALICE Physics Week - Erice, 06.12.2005 Andrea Dainese

  7. pQCD predictions for heavy quark production at the LHC: NLO MNR charm beauty beauty charm 12% 8% Role of pp reference for RAA(at LHC) Exclusive measurements at different energy in AA and in pp  Need to “calibrate the probe”: “translate” the pp reference from 14 to 5.5 TeV ALICE Physics Week - Erice, 06.12.2005 Andrea Dainese

  8. Calibrating the probe in ALICE B  e + X D0 Kp (see C.Bombonati’s talk) NEW! pp, s = 14 TeV ALICE Physics Week - Erice, 06.12.2005 Andrea Dainese

  9. Expected Sensitivity to RAA B  e + X D0 Kp NEW! ALICE Physics Week - Erice, 06.12.2005 Andrea Dainese

  10. mb = 4.8 GeV Low pt (< 6–7 GeV/c) Nuclear shadowing (here EKS98)  Understanding RAA B  e + X D0 Kp NEW! Warning:  5 suppression  2.2 larger statistical errors! ALICE Physics Week - Erice, 06.12.2005 Andrea Dainese

  11. The role of the initial state • Effect of nuclear modification of the initial state PDFs may be tackled by charm measurement in pPb ALICE Physics Week - Erice, 06.12.2005 Andrea Dainese

  12. mb = 4.8 GeV Low pt (< 6–7 GeV/c) Nuclear shadowing (here EKS98) High pt (> 6–7 GeV/c) Only parton energy loss? Understanding RAA B  e + X D0 Kp beware of in-medium hadronisation … ALICE Physics Week - Erice, 06.12.2005 Andrea Dainese

  13. Statistical errors for 107 min. bias Pb-Pb evts The role of hadronisation • Lowish pt D and B mesons may hadronise inside the medium via coalescence no clean study of parton E loss • Up to which pt is this relevant?  Study particle type-dependence of RCP RHIC: • ALICE @ LHC: • kaons and hyperons • (see talks in soft physics sessions) • D meson RCP sensitivity under study E loss only  breakdown of n-quark scaling of v2 can also help to identify “safe” pt region ALICE Physics Week - Erice, 06.12.2005 Andrea Dainese

  14. Heavy-to-light ratios in ALICE in progress: devise how to use to electrons from B to build a RB/h, or RB/D … ALICE Physics Week - Erice, 06.12.2005 Andrea Dainese

  15. Summary • Observation of (large) heavy-quarks quenching at RHIC has boosted the interest for these studies at LHC • ALICE at LHC in excellent position: • dedicated detectors (ITS) • large production cross sections • Promising performance for RAA of D mesons and electrons from B mesons • Other observables need to be studied • muons from B at forward rapidity • use of W’s as reference • heavy-quark jet studies (azimuthal correlations, b-tagged jets) ALICE Physics Week - Erice, 06.12.2005 Andrea Dainese

  16. EXTRA SLIDES ALICE Physics Week - Erice, 06.12.2005 Andrea Dainese

  17. fgPb(x)/fgp(x) a b c xa xa+xb  see talk by R. Grosso xb Nuclear Shadowing and Charm For charm at pt 0: • x1~x2 ~ 10-4 at y = 0 • min(x1,x2) ~ 10-5 at y = 3 Bjorken • Pb nucleus ~ 105 partons (mainly gluons) • ‘they are so close that they fuse’ • Shadowing: suppression of small-x PDFs • Reduces c&b yield at low pt • Look at low-pt D in p-Pb! ALICE Physics Week - Erice, 06.12.2005 Andrea Dainese

  18. LHC LHC RHIC Au-Au 200 GeV Estimates of RAA for D and B • Ingredients: BDMPS quenching weights for heavy quarks + Glauber-based medium geometry + LHC medium density extrapolated on the basis of hadron suppression at RHIC RHIC analysis: A.D., C.Loizides and G.Paic, Eur. Phys. J. Cto appear, hep-ph/0406201. N.Armesto, A.D., C.A.Salgado and U.A.Wiedemann, in preparation. ALICE Physics Week - Erice, 06.12.2005 Andrea Dainese

  19. p-Pb pp Study shadowing in p-Pb at 8.8 TeV? R.Grosso, PhD thesis (2004) ALICE Physics Week - Erice, 06.12.2005 Andrea Dainese

  20. Theoretical Uncertainties(HERA-LHC Workshop) Evaluation of theoretical uncertainties charm beauty MNR code: Mangano, Nason, Ridolfi, NPB373 (1992) 295. ALICE Physics Week - Erice, 06.12.2005 Andrea Dainese

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