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Heavy Flavour in ALICE

Heavy Flavour in ALICE. Giuseppe E Bruno Università di Bari and INFN - Italy. Outline Charm and Beauty at the LHC Physics motivation for open flavour and quarkonia measurements Heavy-flavour program in ALICE Measurements in preparation

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Heavy Flavour in ALICE

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  1. Heavy Flavour in ALICE Giuseppe E Bruno Università di Bari and INFN - Italy Outline 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)

  2. LHC: where? Here Giuseppe E. Bruno

  3. Alice ALICE at LHC: where? Giuseppe E. Bruno

  4. LHC • Running conditions: • + other ions (Sn, Kr, O) & energies (e.g.: pp @ 5.5 TeV) *Lmax (ALICE) = 1031 ** Lint (ALICE) ~ 0.5 nb-1/year Giuseppe E. Bruno

  5. system shadowing NN x-sect (mb) total multiplicity pp 14 TeV 11.2/0.5 1/1 0.16/0.007 Pb-Pb 5.5 TeV (5% cent) 6.6 /0.2 0.65 /0.85 115 /4.6 LHC is a Heavy Flavour Machine! • cc and bb rates • ALICE PPR (NTLO + shadowing) cc bb PbPb/pp PbPb/pp PbPb PbPb pp pp Giuseppe E. Bruno

  6. large cross-sections • low-x (a field of its own!)  accessible x1, x2 regions in the ALICE experiment muon arm muon arm central detector central detector Giuseppe E. Bruno

  7. Charm & beauty as probes • calculable in pQCD; calibration measurement from pp • rather solid ground • caveat: modification of initial state from pp to AA • shadowing ~ 30 % • saturation? • pA reference fundamental! • produced essentially in initial impact • probes of high density phase • no extra production at hadronization • probes of fragmentation • e.g.: independent string fragmentation vs recombination Giuseppe E. Bruno

  8. Probing the medium • quenching vs colour charge • heavy flavour from quark (CR = 4/3) jets • light flavour from (pT-dep) mix of quark and gluon (CR = 3) jets • quenching vs mass • heavy flavour predicted to suffer less energy loss • gluonstrahlung • collisional loss • beauty vs charm • heavy flavour should provide a fundamental cross-check of quenching picture emerging from RHIC Giuseppe E. Bruno

  9. scaledto M. Cacciari et al., hep-ph/0502203 non phot. el. [J.Bielcik @QM05] Large suppression at RHIC! • n.p. electrons ~ as suppressed as expected for c only (no b) • yet, region above 3-4 GeV expected to be dominated by beauty... [Xin Dong@QM05] • disentangling c/b is a must! • e.g. full reconstruction of D vertices Giuseppe E. Bruno

  10. RHIC SPS LHC Quarkonia at LHC: y (cc) &  (bb) • at LHC we should finally be able to tell... • present status: more cc  reco dominates? F.Karsch et al.: PLB637 75 (2006) larger e J/y finally melts? Important: bb cross section will be large; expect 30% J/y originating in B decays • open b measurement in both central det. and µ arm • very similar suppression at RHIC and SPS... • only y’and cc melt? • J/y melting compensated by cc recombination? Giuseppe E. Bruno

  11. TPC Tracking, dEdx The ALICE detector TOF PID TRD Electron ID MUON ARM  tracking ITS Vertexing, Low pt tracking -4 <  < ­2.5 || < 0.9 Giuseppe E. Bruno

  12. Getting Ready for Beam! • Ready to move MUON arm: largest dipole ever TPC (largest ever) installed, ITS moving in Giuseppe E. Bruno

  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 Giuseppe E. Bruno

  14. Impact parameter resolution • d0 resolution Silicon Pixel Detector • 2 layers, R=4 and 7 cm, ~107 channels pt > 1 GeV/c < 60 mm (rf) ~12m asymptotic BEAM (Z) pixel size 50425 m d0 resolution Giuseppe E. Bruno

  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 40 30 D0 D+ 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 Giuseppe E. Bruno

  16. S per 107 central Pb-Pb events S/(S+B) Error composition stat  syst error stat error 11% from overall normalization not included Beauty in the barrel: displaced e’s • Expected ALICE performance (1 month Pb-Pb) • e± identification from TRD and dE/dx in TPC • impact parameter from ITS Giuseppe E. Bruno

  17. Beauty in the barrel: displaced J/ye-e+ • BJ/y+X+e-e+ • This measurement can allow a determination of the dsbb/dpt cross-section down to pt≈0 e-e+ J/yfrom B prompt J/y J/y pseudoproper decay time x x Giuseppe E. Bruno

  18. mb = 4.8 GeV Expected performance on D, B RAA mass dependence colour charge dependence • should clarify the heavy flavour quenching story D0 K-p+ B  e + X 1 year at nominal luminosity (107 central Pb-Pb events, 109 pp events) Giuseppe E. Bruno

  19. 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 Giuseppe E. Bruno

  20. E.g.: quarkonia to dimuons • 1 month Pb-Pb PbPb cent, 0 fm<b<3 fm Expected yields • J/y high statistics: 0-20 GeV/c • y’ poor significance • (1S) & (2S) : 0-8 GeV/c • (3S) ok, but 2-3 runs needed Giuseppe E. Bruno

  21. Summary • Heavy flavours provide us with a very promising tool to study the properties of the strongly interacting medium produced in ultra-relativistic nucleus-nucleus collisions, e.g.: • Open heavy flavour: probe medium density via energy loss • Charmonia & bottomonia: Debye screening vs. recombination • LHC is the right place  very high rates • ALICE is in excellent position: • dedicated detectors (ITS, TRD, MUON) • promising performance for all key measurements Thanks to: F.Antinori, C.Blume, E.Bruna, Z.Conesa, P.Crochet, A Dainese, H.Ding, J.Faivre, M.Lunardon, G.Martinez, M.Masera, F.Prino, R.Turrisi and ALICE “HF & Quarkonia” working group Giuseppe E. Bruno

  22. EXTRA SLIDES Giuseppe E. Bruno

  23. One dedicated HI experiment: ALICE Two pp experiments with HI program: ATLAS and CMS Giuseppe E. Bruno

  24. Heavy flavour at the LHC in AA Heavy flavours are useful probes: • Novelty of the LHC: large cross section SPS→ RHIC→ LHC Hard processes contribute significantly to the total AA cross-section (σhard/σtot=98%): • Bulk properties dominated by hard processes • Very hard probes are abundantly produced • NLO predictions (ALICE baseline for charm & beauty) theoretical uncertainties of a factor 2 FONLO calculations with MNR code: Mangano, Nason, Ridolfi, NPB373 (1992) 295. Giuseppe E. Bruno

  25. b Pb Pb b b b Which Energy Loss? Heavy flavour at the LHC in AA Heavy flavours are useful probes: • Large virtuality Q  happen at initial time(small “formation time”Dt ~ 1/Q << tQGP ~ 510 fm/c ) sample the whole collision history • Heavy quark pT distribution sensitive to many competing nuclear effects • low-pT (<6 GeV/c at LHC) region sensitive to non-perturbative effects (flow, quark coalescence, gluon shadowing, CGC state…) • high-pT region sensitive to jet quenching (mass and/or colour-charge dependence?) Giuseppe E. Bruno

  26. 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 Giuseppe E. Bruno

  27. 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 Giuseppe E. Bruno

  28. Quarkonia to dielectrons • 1 month Pb-Pb di-electron |h|<0.9 Giuseppe E. Bruno

  29. Quarkonia Performance Bkg input: dNch/dy=4000 in central Pb-Pb. for 1 month

  30. Quarkonia: mass spectra • Measured both in the di-electron (midrapidity, TRD) and di-muon (forward rapidity, MUON) channel di-muon -4<h<-2.5 di-electron |h|<0.9 J/y family  family 1 month at nominal luminosity (107 central Pb-Pb events) Mμμ(GeV/c) Mμμ(GeV/c) Giuseppe E. Bruno

  31. 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) Giuseppe E. Bruno

  32. Heavy flavour jets? 2 GeV20 GeV 100 GeV 200 GeV Mini-Jets 100/event 1/event 100k/month • Well visible event-by-event! e.g. 100 GeV jet + underlying event • For high energy jets: Nb ~ Nu,d • heavy flavour rich! • b-tagged jets? • study quenching of b jets! Giuseppe E. Bruno

  33. Proposed ALICE EMCAL • To improve the capabilities in triggering and measurement of high energy jets • EM Sampling Calorimeter (STAR Design) • Pb-scintillator linear response • -0.7 < h < 0.7 • p/3 < F < p (opposite to PHOS) • Energy resolution ~15%/√E • Rails already installed • Support structure funded by DoE, • to be installed this summer • 10 +1/2+1/2 Supermodules (SM) • 1 SM = 24x12 modules • 1 module = 4 channels : • 1.2 x 104 total channels (granularity) Giuseppe E. Bruno

  34. EMCAL • Single detector : 6x6x25 cm3 shashlik 1.44mm Pb/1.76mm scintillator sampling • 77 layers = 20 Xo • WLS fiber+APD readout • Front End Electronics mainly developed for TPC and PHOS • First SM to be ready for 2008 run • Full Calorimeter to be completed for 2010 run EMCAL Project: Italy (LNF, Ct) + France + US Giuseppe E. Bruno

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