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Heavy Flavour in ALICE

Heavy Flavour in ALICE. Federico Antinori (INFN Padova & CERN) for the ALICE Collaboration. Contents. The LHC, Heavy Flavours and ALICE or “ALICE in Wonderland” Benchmark channels D 0  K - p + B  e + X B  µ + X Additional measurements under investigation D +  K - p + p +

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Heavy Flavour in ALICE

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  1. Heavy Flavour in ALICE Federico Antinori (INFN Padova & CERN) for the ALICE Collaboration Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  2. Contents • The LHC, Heavy Flavours and ALICE • or “ALICE in Wonderland” • Benchmark channels • D0 K-p+ • B  e + X • B  µ + X • Additional measurements under investigation • D+ K-p+ p+ • B  J/y + X • v2 • Ds • b tagged jets • Coming up: pp • Conclusion Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  3. The LHC, Heavy Flavours and ALICE Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  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 Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  5. Heavy Flavour @ LHC 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 • cc and bb rates • ALICE PPR (NTLO + shadowing) cc bb PbPb/pp PbPb/pp PbPb PbPb pp pp Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  6. large cross-sections • low-x (a field of its own!)  accessible x1, x2 regions in the ALICE experiment muon arm central detector Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  7. study medium with probes of known colour charge and mass • e.g.: energy loss by gluon radiation expected to be: • parton-specific: stronger for gluons than quarks (colour charge ratio = 9/4) • flavour-specific: stronger for lighter than for heavier quarks (dead-cone effect) • study effect of medium on fragmentation (no extra production of c, b at hadronization) • independent string fragmentation vs recombination • e.g.: D+s/D+ • + measurement important for quarkonium physics • open QQ production natural normalization for quarkonium studies • B meson decays non negligible source of non-prompt J/y at LHC Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  8. Large suppression at RHIC! scaled to M. Cacciari et al., hep-ph/0502203 non phot. el. [J.Bielcik @QM05] • 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 Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  9. By the way: the factor 9/4? • energy loss should be proportional to: CR = 4/3 for q, = 3 for g • at RHIC, at 6-8 GeV pT: x ~ 10-1 • large quark contribution also for light flavours? • at LHC, at same pT: x ~ a few 10-4 • quark contribution negligible Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  10. ALICE Set-up Size: 16 x 26 meters Weight: 10,000 tons TOF TRD HMPID ITS PMD Muon Arm PHOS TPC

  11. ALICE Status • Timeline: • Installation & commissioning ongoing • Global commissioning in December & February (cosmics) • April 2008 on: cosmics, then pp run (commissioning  physics) • followed by first Pb-Pb run (√s = 5.5 TeV, L = 5·1025 cm-2s-1) • Startup configuration: • complete: ITS, TPC, TOF, HMPID, muon arm, PMD, trigger dets (V0, T0, ZDC, Acorde) • partially complete: PHOS (3/5), TRD (5/18), DAQ/HLT (20-30%) Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  12. Tracking |η| < 0.9: B = 0.4 T TRD TPC ITS with: - Si pixel - Si drift - Si strip Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  13. Inner Tracking System (ITS) longitudinal coverage: |h| < 1 (tracking), |h|<2 (multiplicity) Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  14. ITS Installation Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  15. rf: 50 mm z: 425 mm PIXEL CELL  9.8 M Two layers: r = 4 cm r = 7 cm Silicon Pixel Detector (SPD) Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  16. Expected resolution on track impact parameter • track impact parameter (d0) Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  17. Benchmark channels Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  18. D0 K-p+ statistical. systematic. • expected ALICE performance • S/B ≈ 10 % • S/(S+B) ≈ 40 (1 month Pb-Pb running) pT - differential Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  19. Beauty to electrons • Expected ALICE performance (1 month Pb-Pb) • e± identification from TRD and dE/dx in TPC • impact parameter from ITS S/(S+B) S per 107 central Pb-Pb events Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  20. Electrons (from b) pt spectrum Error composition stat  syst error stat error 11% from overall normalization not included Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  21. Expected performance on D, B RAA mb = 4.8 GeV 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) Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  22. Beauty to single muons high mass mm low mass mm • expected in the muon arm  very high statistics and heavy flavour purity expected Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  23. Beauty to dimuons µ-+ X X + µ+ B B B µ+ + D + X µ-+ X • Two main sources: “BDSAME” “BBDIFF” • Consistency check! Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  24. Additional measurements under investigation Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  25. D+ K-p+p+ • Preliminary study: performance comparable to that for D0K-p+ Pb-Pb significance ~ 30 (1 month) Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  26. Ds+ • Ds+as probe of hadronization? • from string fragmentation: cs / cd ~ 1/3 • after decays: Ds+ (cs) / D+ (cd) ~ 0.6 • from recombination: cs / cd ~ N(s) / N(d)  how large at LHC? • experimentally accessible? • D+ (ct ~ 310 µm)  K-p+p+ with BR ~ 9.2 % • in Alice: expect similar performance as for D0 K-p+ • Ds+ (ct ~ 150 µm)  K-K+p+ with BR ~ 4.4 % • but mostly resonant decays: Fp+ or K0*K+ (non resonant only 20 %)  favours bkgnd rejection (for D+  K-p+p+, non-resonant ~ 96 %) • may be well visible (expecially if Ds+/D+ is large!) • Under study! Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  27. Heavy Flavour v2 • v2 = azimuthal anisotropy  elliptic flow • can get charm v2 from • direct charm elliptic flow • non-flowing c recombining with flowing matter • azimuthally dependent energy loss • ...? • in general, v2 0 if charm “strongly coupled” with azimuthally asymmetric medium... Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  28. Non photonic el. v2 @ RHIC [Xin Dong@QM05] [S.Butsyk@QM`05] • to what extent can one accommodate small v2 with large suppression? Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  29. Reconstructed D v2 at LHC? • Full reconstruction of D decays at LHC • qualitatively different measurement from non-photonic electrons! • better correlation with original heavy-quark momentum • b vs c • First indications from preliminary studies in ALICE: expected error ~ few % (D v2) Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  30. B  J/y + X • More “exclusive” than B  e/µ + X • better handle on B momentum distribution • Preliminarypp study: pseudoproper decay time (à la CDF) CDF (data) pT>0 ALICE (prelim. simulation)

  31. 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! • Preliminary look: impact parameter tagging looks promising (full simulation needed) Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  32. Coming up: pp Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  33. Example: D0 in pp • D0 K-p+ • 1 year run  ~ 109 events • ~ 20 shifts, 10 hrs each  a few 107 events • reach out to 12 GeV or so Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  34. Example: B  e + X in pp • electron id in TRD and TPC, electron impact parameter from ITS Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

  35. Conclusion • Heavy flavours kindly provide us with a very promising tool to study the properties of the strongly interacting medium produced in ultra-relativistic nucleus-nucleus collisions • At LHC •  very high rates •  very extended pT range •  well developed jets • ALICE is well equipped for heavy flavour physics Federico Antinori - LBNL Heavy Quark Workshop - 3 November 2007

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