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ALICE potential for heavy-flavour physics

SQM 2007 Levo č a, Slovakia, June 24-29, 2007. ALICE potential for heavy-flavour physics. Andrea Dainese INFN – Legnaro for the ALICE Collaboration. Contents. Charm and beauty at the LHC Physics motivation for open flavour and quarkonia measurements Heavy-flavour program in ALICE

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ALICE potential for heavy-flavour physics

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  1. SQM 2007 Levoča, Slovakia, June 24-29, 2007 ALICE potential for heavy-flavour physics Andrea Dainese INFN – Legnaro for the ALICE Collaboration SQM 2007 - Levoca, 28.06.07 Andrea Dainese

  2. Contents • Charm and beauty at the LHC • Physics motivation for open flavour and quarkonia measurements • Heavy-flavour program in ALICE • Measurements in preparation • Examples of expected performance (charm & quarkonia) • more on beauty  J.Faivre’s talk SQM 2007 - Levoca, 28.06.07 Andrea Dainese

  3. factor ~2 uncertainty large LHC: hard cross sectionslots of heavy quarks! • NLO predictions (ALICE baseline for charm & beauty) MNR code (NLO): Mangano, Nason, Ridolfi, NPB373 (1992) 295. beauty charm * M.Mangano SQM 2007 - Levoca, 28.06.07 Andrea Dainese

  4. charm beauty Cartoon The charm of small-x gluons • Probe unexplored small-x region with HQs at low pt and/or forward y s=14 TeV D mesons pt0, y=0 J/ypt0, y4 s=14 TeV x~10-4 x~10-6 • Charm measurements at low-pt or forward y  Window on high-density PDFs phenomenology: gluon saturation / recombination effects / CGC SQM 2007 - Levoca, 28.06.07 Andrea Dainese

  5. Parton Energy Loss by • medium-induced gluon radiation • collisions with medium gluons pred: u,d,s: m~0, CR=4/3 (difficult to tag at LHC) g: m=0, CR=3 > E loss, dominant at LHC c: m~1.5 GeV, CR=4/3 small m, tagged by D’s b: m~5 GeV, CR=4/3 large mass, < E loss QCD medium Heavy quarks as medium probes:Energy Loss q: colour triplet • Parton Energy Loss by • medium-induced gluon radiation • collisions with medium gluons g: colour octet Q: colour triplet Dokshitzer and Kharzeev, PLB 519 (2001) 199. Armesto, Salgado, Wiedemann, PRD 69 (2004) 114003. Djordjevic, Gyulassy, Wicks, nucl-th/0512076 SQM 2007 - Levoca, 28.06.07 Andrea Dainese

  6. massive heavy-to-light ratio Energy loss, from RHIC to LHC (I) Radiative energy loss (BDMPS): charm ~ m=0 quark  probe colour charge dependence; beauty  probe mass dependence Pb-Pb 5.5 TeV Au-Au 200 GeV Armesto, Cacciari, Dainese, Salgado, Wiedemann, “Last Call for LHC Predictions” workshop SQM 2007 - Levoca, 28.06.07 Andrea Dainese

  7. Energy loss, from RHIC to LHC (II) Heavy quarks (esp. beauty) may help to disentangle relative importance of radiative and collisions losses see also talk by W.Horowitz Wicks, Gyulassy, “Last Call for LHC Predictions” workshop SQM 2007 - Levoca, 28.06.07 Andrea Dainese

  8. Energy loss, from RHIC to LHC (III) Conceptually different approach: Fragmentation & dissociation of heavy-flv hadrons inside QGP D B D+B I.Vitev, A.Adil, “Last Call for LHC Predictions” workshop SQM 2007 - Levoca, 28.06.07 Andrea Dainese

  9. at higher pt: path-length dependence of E loss in almond-shaped medium RHIC LHC Armesto, Cacciari, Dainese, Salgado, Wiedemann, “Last Call for LHC Predictions” workshop Heavy quarks as medium probes:Azimuthal asymmetry (v2) • v2 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 van Hees, Rapp, Greco, “Last Call for LHC Predictions” workshop SQM 2007 - Levoca, 28.06.07 Andrea Dainese

  10. enhanced regeneration enhanced suppression 30 SPS RHIC LHC Quarkonia at LHC: y (cc) &  (bb) • J/ suppression & regeneration? • c, y’ suppression (J/ TD ~ 1.5-2 Tc)? TLHC >> J/ TD •  melts only at LHC • ’ TD ~ J/ TD • Small  regeneration • ’ can unravel J/ • suppression VS regeneration SQM 2007 - Levoca, 28.06.07 Andrea Dainese

  11. The ALICE Detector Size: 16 x 26 meters Weight: 10,000 tons |h| < 0.9, B = 0.5 T TPC + silicon tracker g,e, p, K, p identification -4 < h < -2.5 muons ALICE Collaboration: >1000 people, 30 countries, ~ 90 Institutes SQM 2007 - Levoca, 28.06.07 Andrea Dainese

  12. Getting Ready for Beam! • Ready to move MUON arm: largest dipole ever TPC (largest ever) installed, ITS moving in SQM 2007 - Levoca, 28.06.07 Andrea Dainese

  13. D0 Kp D+ Kpp Ds KKp D*  D0p D0 Kpr LcpKp • D0 Kp D+ Kpp Ds KKp D*  D0p D0 Kpr LcpKp • D0 Kp D+ Kpp Ds KKp D*  D0p D0 Kpr LcpKp TOF (K/p id) under study under study under study TPC (tracking) ITS (vertexing) TPC (tracking) m K p MUON (tracking,id) • B  e+X B5 pr. BJ/yee • B  e+X B5 pr. BJ/yee ITS (vertexing) under study under study • B m+X ITS (vertexing) TPC (tracking e/p id) TRD (e/p id) e Open charm and beauty SQM 2007 - Levoca, 28.06.07 Andrea Dainese

  14. rf: 50 mm rec. track e z: 425 mm Primary Vertex PIXEL CELL B < 60 mm (rf) for pT > 1 GeV/c d0 X Two layers: r = 4 cm r = 7 cm Vertexing: track d0 resolution Resolution mainly provided by the 2 layers of silicon pixels  9.8 M SQM 2007 - Levoca, 28.06.07 Andrea Dainese

  15. pair of opposite-charge tracks with large impact parameters • good pointing of reconstructed D momentum to the primary vertex • large distance (dPS) between primary and secondary vertex • good pointing of reconstructed D momentum to the primary vertex D0 D+ Invariant mass analysis 50 D0 D+ 40 30 20 10 1 year at nominal luminosity (109 pp events, 107 central Pb-Pb events) Charm reconstruction: D0 K-p+ & D+ K-p+p+ • Two vertexing algos with full error-matrix treatment • Large combinatorial background (dNch/dy=6000 in Pb-Pb simul.) • Main selection: displaced-vertex selection SQM 2007 - Levoca, 28.06.07 Andrea Dainese

  16. J/y pseudoproper decay time (pt>5GeV) J/y e+e- primary secondary Beauty in the barrel:displaced e’s, displaced J/yee • Excellent electron identification capabilities (TPC and TRD) • Displaced electrons/di-electrons from B decays tagged by an impact parameter cut (ITS) see talk by J.Faivre SQM 2007 - Levoca, 28.06.07 Andrea Dainese

  17. Charm and Beauty E Loss : RAA D0 Kp D+ Kpp B  e + X mC = 1.2 GeV mC = 0 B  e E loss calc.: Armesto, Dainese, Salgado, Wiedemann mb = 4.8 GeV 1 year at nominal luminosity (107 central Pb-Pb events, 109 pp events) SQM 2007 - Levoca, 28.06.07 Andrea Dainese

  18. probes colour-charge dep. of QCD energy loss probes mass dep. of QCD energy loss Heavy-to-light ratios E loss calc.: Armesto, Dainese, Salgado, Wiedemann 1 year at nominal luminosity (107 central Pb-Pb events, 109 pp events) SQM 2007 - Levoca, 28.06.07 Andrea Dainese

  19. Charm v2: D+ example • First estimate of statistical errors on D+ v2: • best sensitivity at intermediate pt: 3 – 7 GeV/c  charm recombination • Under study: performance with D0 + D+ 2107 min.bias evts 2107 6<b<9 fm evts v2 calc. from Ko et al. SQM 2007 - Levoca, 28.06.07 Andrea Dainese

  20. RCP ALICE muon spectrometer acc.: -4 < h < -2.5, pt > 1 GeV, p > 4 GeV Wm (medium-blind reference) dominates for pt > 30 GeV/c!! b quark E loss thin: no mass effect thick: mass effect Beauty via (forward) muons • Muons “identified” in the spectrometer (-4 << -2.5)  single muons in the spectrometer: b dominates for pt > 2-3 GeV/c inner bars: stat. errors outer bars: syst. errors Pb-Pb 0-5% (1 month) SQM 2007 - Levoca, 28.06.07 Andrea Dainese

  21. ITS (vertexing) TPC (tracking) TRD (e/p id) e e m m MUON (tracking,id) Quarkonia Measured both in the di-electron (midrapidity, TRD) and di-muon (forward rapidity, MUON) channel SQM 2007 - Levoca, 28.06.07 Andrea Dainese

  22. Quarkonia Performance Bkg input: dNch/dy=4000 in central Pb-Pb. for 1 month SQM 2007 - Levoca, 28.06.07 Andrea Dainese

  23. Medium effect on Quarkonia:Quarkonia/BB , Quarkonia RAA • Normalization of quarkonia yields: • BB yield (from intermediate-mass di-leptons), but b E loss? • Possible alternative: RAA (à la PHENIX), but different c.m.s. energy, need p-Pb for initial-state effects Plots for m+m- channel SQM 2007 - Levoca, 28.06.07 Andrea Dainese

  24. Summary • LHC: heavy quarks and quarkonia factory • Heavy quarks as probes of QCD in extreme conditions • low pt: probe small-x structure of p and nucleus • intermediate pt: probe medium thermalisation (reco/flow) • high pt: probe medium density via energy loss • Charmonia & bottomonia as probes of QCD phase transition • ALICE in excellent position: • dedicated detectors (ITS, TRD, MUON) • promising performance for all key measurements Thanks to: F.Antinori, C.Blume, C.Bombonati, E.Bruna, G.E.Bruno, Z.Conesa, P.Crochet, H.Ding, J.Faivre, R.Guernane, M.Lunardon, G.Martinez, M.Masera, F.Prino, R.Turrisi and ALICE “HF & Quarkonia” working group SQM 2007 - Levoca, 28.06.07 Andrea Dainese

  25. EXTRA SLIDES SQM 2007 - Levoca, 28.06.07 Andrea Dainese

  26. 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   SQM 2007 - Levoca, 28.06.07 Andrea Dainese

  27. 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 SQM 2007 - Levoca, 28.06.07 Andrea Dainese

  28. di-muon -4<h<-2.5 J/y family  family di-electron |h|<0.9 Mμμ(GeV/c) Mμμ(GeV/c) Quarkonia: mass spectra Measured both in the di-electron (midrapidity, TRD) and di-muon (forward rapidity, MUON) channel 1 month at nominal luminosity (107 central Pb-Pb events) SQM 2007 - Levoca, 28.06.07 Andrea Dainese

  29. Suppression Scenarii • 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 . Ph. CROCHET, F, GUERIN, R. GUERNANE, S. GRIGORYAN et al. PRC72 034906(2005) Hep-ph/0507084(2005) Good sensitivity J/Y, (1S) & (2S) SQM 2007 - Levoca, 28.06.07 Andrea Dainese

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