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Heavy Flavours in ALICE

Heavy Flavours in ALICE. Giuseppe E Bruno Università di Bari and INFN – Italy for the ALICE collaboration. Outline Charm and Beauty at the LHC Heavy-flavour program in ALICE Measurements in preparation Examples of expected performance Conclusions. LHC. Running conditions:

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Heavy Flavours in ALICE

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  1. Heavy Flavours in ALICE Giuseppe E Bruno Università di Bari and INFN – Italy for the ALICE collaboration Outline Charm and Beauty at the LHC Heavy-flavour program in ALICE Measurements in preparation Examples of expected performance Conclusions

  2. 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

  3. 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 factor ~2 uncertainty Heavy Flavour @ LHC • cc and bb rates • NLO predictions (ALICE baseline) beauty charm * M.Mangano Giuseppe E. Bruno

  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 Giuseppe E. Bruno

  5. 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

  6. 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 Giuseppe E. Bruno

  7. 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

  8. The ALICE detector • Acceptance: η<|0.9| • (di)electrons: J/, ’, , ’, ’’ open charm & beauty • hadrons: D±, D0, … • Acceptance: -4<η<-2.5 • (di)muons: J/, ’, , ’, ’’ open charm & beauty TOF PID TRD Electron ID TPC Tracking, dE/dx ITS Vertexing, Low pt tracking • electron-muon coincidences: open charm & beauty MUON Spectrometer Physics at LHC - Philippe Pillot Giuseppe E. Bruno 8

  9. ALICE Detector Installation mid 2008 Complete: ITS, TPC, TOF, HMPID, FMD, T0, V0, ZDC, Muon arm, Acorde Partial installation: 1/5 PHOS 4/18 TRD 9/48 PMD 0/6 EMCAL ~ 40% DAQ/HLT ALICE Status Installation targets met by mid 2008 9

  10. D0 Kp D+ Kpp Ds KKp D*  D0p D0 Kppp LcpKp TOF (K/p id) under study TPC (tracking) K p ITS (vertexing) Hadronic charm D0 Giuseppe E. Bruno

  11. rf: 50 mm z: 425 mm PIXEL CELL Impact parameter < 50 mm for pt > 1.5 GeV Two layers: r = 4 cm r = 7 cm Impact parameter resolution • d0 = distance of closest approach between track and primary vertex • d0 resolution mainly provided by the two innermost layers of the ITS (pixels) • R=4 and 7 cm, ~107 channels Silicon Pixel Detector BEAM (Z) pixel size 50425 m d0 resolution Giuseppe E. Bruno

  12. pair of opposite-charge tracks with large impact parameters • good pointing of reconstructed D momentum to the primary vertex D0 Invariant mass analysis Charm reconstruction: D0 K-p+ • Two vertexing algorithms with full error-matrix treatment • Large combinatorial background (dNch/dy=6000 in Pb-Pb simul.) • Main selection: displaced-vertex selection Giuseppe E. Bruno

  13. rec. track ITS (vertexing) TPC (tracking + e/p id) TRD (e/p id) e e Primary Vertex B X d0 Beauty from single electrons Be+X Giuseppe E. Bruno

  14. 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

  15. TRD (e/p id) TPC (tracking + e/p id) e+ e- ITS (vertexing) y e+ e- J/y X B x Beauty from displaced J/y BJ/y+X e-e+ Giuseppe E. Bruno

  16. 109 pp events 350 tot 300 Events/10 MeV Events/10 MeV 250 J/y 200 bkg 150 100 50 2.8 2.9 3.0 3.1 3.2 m(e+,e-) [GeV] Beauty in the barrel: displaced J/ye-e+ • Analysis based on a simultaneous fit of • the invariant mass spectrum Giuseppe E. Bruno

  17. 102 Entries/100mm 10 102 1 Entries/100mm 2<pT<3 Gev 10 -2000 -1000 0 1000 2000 3000 x [mm] 1 -2000 -1000 0 1000 2000 3000 x [mm] 109 pp events J/y from B tot J/y ALICE bkg sum pT>0 pT>5 Gev 103 102 Entries/100mm 10 CDF 1 -2000 -1000 0 1000 2000 3000 x [mm] Beauty in the barrel: displaced J/ye-e+ • Analysis based on a simultaneous fit of • the invariant mass spectrum • an “impact parameter” to separate prompt from detached J/y, e.g. pseudo- proper decay time (à la CDF) D.Acosta et al Phys. Rev. D 71 (2005) 032001 • This measurements can allow a determination of the dsbb/dpt cross-section down to pt≈0 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 mechanism 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. Quarkonia Performance Bkg input: dNch/dy=4000 in central Pb-Pb. for 1 month

  21. Many other channels • charm: exclusive hadronic channels • D0  K (tested in pp & PbPb) • D+  K (tested in pp & PbPb) • D±s  KK (under study) • D*  D0 (under study) • D0  K (under study) • c  pK (under study) • charm & bottom: semi-inclusive leptonic channels • c  l + X (à la CDF & D0) • b  l + X (à la CDF & D0) • b  J/ + X (à la CDF & D0) • bbbar  J/ + l (under study) • bbbar  3 (should work in pp) • bbbar  l+l-,l-l+ (Bchain & BBdiff) • bbbar  l-l-,l+l+ (Bchain & B osc.) Giuseppe E. Bruno

  22. 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 • promising performance for all key measurements Giuseppe E. Bruno

  23. Thank you First interaction in ALICE: 11.9.2008 (beam – pixel collisions) Giuseppe E. Bruno

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