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Heavy-quark and Quarkonia production in high-energy heavy-ion collisions

Heavy-quark and Quarkonia production in high-energy heavy-ion collisions. Andr é Mischke. 1 st International Workshop on Multiple Partonic Interactions at the LHC Universita’ degli Studi di Perugia, Perugia, Italy 27-31 October 2008. MPI@LHC’08. Outline.

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Heavy-quark and Quarkonia production in high-energy heavy-ion collisions

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  1. Heavy-quark and Quarkonia production in high-energy heavy-ion collisions André Mischke 1st International Workshop on Multiple Partonic Interactions at the LHC Universita’ degli Studi di Perugia, Perugia, Italy 27-31 October 2008 MPI@LHC’08

  2. Outline • In-medium production of heavy flavor at RHIC • Open heavy flavour • - charm cross section • nuclear modification factor • two particle correlations • Quarkonia (J/ and ) • Perspectives Andre Mischke (UU)

  3. Matter in extremes: The QGP • Study strongly interacting matter under extreme conditions • high temperature • high density • Lattice QCD predicts a phase transition from hadronic matter to a deconfined state, the Quark-Gluon Plasma • Experimental access via high energy heavy-ion collisions Quark-GluonPlasma Temperature RHIC Hadronic matter Baryon density Andre Mischke (UU)

  4. Probing the hot, dense QCD matter with jets Au+Au collision p+p collision • Hard processes occur in the early stage of the collision (pQCD) • Hard scattered partons traverse through the medium & interact strongly • General picture: Energy loss via medium induced gluon radiation (Bremsstrahlung) Energy density at RHIC (Bjørken estimate) more than 30 times normal nuclear matter density Andre Mischke (UU)

  5. Results from light quarks photons light hadrons • What have we learnt so far ? • Central Au+Au collisions produce dense, rapidly thermalizing matter • Jet quenching in opaque medium  strongly interacting plasma (sQGP) • Produced matter shows collective behavior; well described by ideal hydrodynamics (no viscosity) “Perfect Liquid” • Relevant degrees of freedom seem to be partonic(constituent quark scaling) Andre Mischke (UU)

  6. Limitations of RAA ? K.J. Eskola et al., Nucl. Phys. A747 (2005) 511 light hadrons central RAA data increasing density • Jet quenching well described by energy loss models • Surface bias effectively leads to saturation of RAA with density • Limited sensitivity to the region of highest energy density • Needed: - insensitive trigger particles: Prompt photons - probes with higher penetrating power:Heavy quarks Andre Mischke (UU)

  7. parton hot and dense medium Energy loss of heavy quarks in QCD matter • Large mass • primarily gg  QQ; • production rates from pQCD - sensitivity to initial state gluon distribution •  To be verified for heavy-ion collisions • Heavy quarks • - ”grey probes” • energy loss due to suppression of small angle gluon radiation (dead-cone effect)Dokshitzer & Kharzeev, PLB 519, 199 (2001) • Which questions can be addressed ? • - Energy loss mechanism, degree of thermalization: Open heavy flavor • - Deconfinement (dissociation in QGP), degree of thermalization: Hidden heavy flavor Wicks et al, NPA784, 426 (2007) Andre Mischke (UU)

  8. Detection of heavy-flavor particles Full reconstruction of open charmed mesons D0 K- +p+(BR = 3.89%) direct clean probe: signal in invariant mass distribution difficulty: large combinatorial background; especially in a high multiplicity environment event-mixing and/or vertex tracker needed Semi-leptonic decay of charm and bottom mesons* c  lepton + X (BR = 9.6%) D0 e+ + X (BR = 6.87%) D0m+ + X (BR = 6.5%) b  lepton + X (BR = 10.9%) robust electron trigger needs handle on photonic background called non-photonic electron * F.W. Buesser et al. (CCRS), NPB 113, 189 (1976) Andre Mischke (UU)

  9. Detectors at RHIC Au+Au at sNN = 200 GeV • Large acceptance magnetic spectrometer • High resolution TPC, ToF, CTB and EMC • Open heavy flavors • hadronic reconstruction of D mesons using TPC + ToF • muon identification with TPC + ToF • electrons • Quarkonia states using special triggers • Designed for leptonic measurements • DC, PC, TEC, RICH, EMC and Muon tracking  low radiation length • Open heavy flavors • muons (muon arms at forward rapidities) • electrons • Quarkonia states Andre Mischke (UU)

  10. Electron identification Data MC (p0+Ke3) p0 Dalitz and g conversion (MC) Ke3 decays (MC) • Phenix • Electromagnetic calorimeter and RICH at mid rapidity • pT< 5 GeV/c • STAR • ToF + TPC • pT< 4 GeV/c • EMCal + TPC • pT > 1.5 GeV/c E/p Andre Mischke (UU)

  11. Electron background sources Photonic electron background -g e+ + e-(small for Phenix) - p0g + e+ + e- - h, w, f, etc. Phenix is almost material free  their background is highly reduced compared to STAR Background is subtracted by two independent techniques - very good consistency between them - converter method (1.68% X0) - cocktail method STAR determines photonic background using invariant mass Phenix e+ e- e- dca  mass (GeV/c2) STAR Andre Mischke (UU)

  12. Non-photonic electron spectra Phys. Rev. Lett. 98, 172301 (2007) Phys. Rev. Lett. 98 (2007) 192301 Au+Au Au+Au 0-5% 10-40% 40-80% d+Au p+p p+p • Spectra measured up to 10 GeV/c • Integrated yield follows binary collision scaling • Yield strongly suppressed at high pT for central Au+Au Andre Mischke (UU)

  13. Charm cross section in Phenix c dominant b dominant after subtraction of cocktail • Channels: • Electrons • Di-electrons • Start looking at open charm: D0 K+p-p0, where p0 gg • Comparison to charm, bottom and Drell-Yan from PYTHIA • In good agreement with single electrons scc= 518 ± 47 (stat) ± 135 (sys) ± 190 (model) mb sbb= 3.9 ± 2.4 (stat) +3/-2 (sys) mb Andre Mischke (UU)

  14. Open charm reconstruction in STAR d+Au 200 GeV PRL 94 (2005) 062301 Cu+Cu 200 GeV A. Shabetai, QM 2008 Au+Au 200 GeV arXiv:0805.0364 [nucl-ex] • First identified D mesons in heavy-ion collisions • Current method has its kinematical limits Andre Mischke (UU)

  15. Charm cross section in STAR Use all possible signals - D0 mesons - electrons - muons Charm cross section is well constrained - 90% of total cross section - direct measurement - D0 mesons and muons constrain the low-pT region p m Andre Mischke (UU)

  16. Total charm cross section centrality • Both STAR and Phenix are self-consistent • STAR data factor of ~2 larger than Phenix data work in progress… • Cross section follows binary collision scaling  charm exclusively produced in initial state Andre Mischke (UU)

  17. RAA for non-photonic electrons  a surprise ! + STAR, prel.: Cu+Cu 200 GeV, 0-54% + STAR Phenix • RAA(e) ≈RAA (h) at pT> 6 GeV/c  not in line with expectations from dead-cone effect • Models implying D and B energy loss are inconclusive yet • collisional energy loss • dissociation in the medium may play a role • Smoothly decrease from peripheral to central Au+Au • Cu+Cu data fits into systematics Andre Mischke (UU)

  18. Heavy-flavour correlations • e–D0 azimuthal angular correlations • - D/B discrimination • - sensitive to NLO processes for charm • Significant bottom contribution to non-photonic electrons • Charm content in jets ~5% essentially from B decays only 75% from charm 25% from beauty A. M., arXiv:0807.1309 (hep-ph) M. Cacciari et al., PRL 95, 122001 (2005) pQCD: Large uncertainty in D/B crossing point: pT = 3-10 GeV/c Andre Mischke (UU)

  19. “Melting” of Quarkonia states in QGP Charmonia:J/, ’, cBottomonia:(1S), (2S), (3S)‏ • Color screening of static potential between heavy quarks (λD) • - J/suppressionMatsui and Satz, Phys. Lett. B 178 (1986) 416 • Suppression of states is determined by TC and their binding energy •  QCD thermometer • Lattice QCD: Evaluation of spectral fcts • Sequential disappearance of states H. Satz, HP2006 Andre Mischke (UU)

  20. RAA for J/ in Phenix  a surprise ! • Comprehensive J/ measurements in p+p, d+Au, Cu+Cu and Au+Au • RAA(RHIC, y=0) ≈ RAA(SPS) • RAA(y=0) > RAA (y>1.7) • Possible mechanisms • - final state: recombination? • - initial state: cold nuclear effects?  Run8 d+Au data centrality Andre Mischke (UU)

  21. J/ spectra and RAA in STAR • J/ p+p cross sections: consistent within ~1 up to 10 GeV/c • J/ production in Cu+Cu at pT>5 GeV/c (fit): RAA = 0.9 ± 0.2(stat.) • Contrast to AdS/CFT prediction • Due to Cronin? – Run8 d+Au data Andre Mischke (UU)

  22. Disentangle contributions to J/ via correlations preliminary 5.4 signal (S+B)/B: 54/14 • J/-h azimuthal correlations sensitive to source of J/UA1, PLB 200, 380 (1988) and 256, 112 (1991) • B  J/ feed-down <15% • Phenix: J/yfrom y’ = 8.6 ± 2.5% Andre Mischke (UU)

  23.  cross-section in p+p Counts d/dy (nb) y preliminary preliminary • STAR run 6 p+p at sNN = 200 GeV • 3σ signal • (1s+2s+3s)  e+e-: • BReed/dy = 91 ± 28(stat.) ± 22(sys.) pb • Cross section consistent with NLO pQCD calculations and world data trend • Upsilon RAA; signal already seen in Au+Au ! Andre Mischke (UU)

  24. Summary • Charm production cross-section • important baseline measurements for Quarkonia studies • follows binary collision scaling and agrees with FONLL within errors • Non-photonic electron spectra • energy loss in heavy-ion collision is much larger than expected • Electron-D0 azimuthal correlations • - B and D contributions comparable at pT>5 GeV/c & consistent with FONLL • J/ • - p+p: cross section up to 14 GeV/c • - Cu+Cu: RAA~1 at high pT– more accurate measurements • Quarkonia •  cross-section in pp consistent with pQCD and world data • first  signal in Au+Au • Next: absolute cross-section in p+p, d+Au (run 8) and Au+Au and RAA Run 7 Au+Au data Andre Mischke (UU)

  25. Perspectives: RHIC II • STAR and Phenix upgrades visioning heavy-flavor measurements • STAR heavy-flavour tracker and full ToF: Open charm spectra at higher pT and flow measurements • Phenix silicon vertex tracker • RHIC II upgrade will provide more luminosity (~2012) Andre Mischke (UU)

  26. Perspectives: ALICE at LHC statistical. systematic. • D0 K • D+ K-++ • D,B  e + X S/B ≈ 10 % S/(S+B) ≈ 40 (1 month Pb-Pb running) TI2 injection test: muons from beam dump ALICE Inner Tracker System Andre Mischke (UU)

  27. Backup Andre Mischke (UU)

  28. The ALICE detector A Large Ion Collider Experiment Size: 16 x 26 meters Weight: 10.000 tons lead beam lead beam Silicon Strip Detector • Especially designed for measurements in heavy-ion collisions • Utrecht/NIKHEF group built a part of the inner particle tracker • Full azimuthal coverage Andre Mischke (UU)

  29. Total bottom cross section from Phenix • Several extrapolations used (pT, rapidity and mass) • Different methods agree • Reasonably good agreement with NLO pQCD Andre Mischke (UU)

  30. D* - jet measurement • D* - Jet azimuthal correlation: - visible near side peak. • Raw fragmentation function: - D(z), where z = pL(K)/E jet - Ejet found and corrected using cone algorithm. - Match of data and LO Monte Carlo at high z - Excess at low z: NLO contribution. Andre Mischke (UU)

  31.  trigger in STAR • Sample -triggered event • e+e- candidate • mee = 9.5 GeV/c2 • cosθ = -0.67 • E1 = 5.6 GeV • E2 = 3.4 GeV Offline: charged tracks + EMC tower • Fast L0 Trigger (Hardware) • Select events with at least one  high energy tower (E~4 GeV) • L2 trigger (Software) • Clustering, calculate mee, cos q. • Very clean to trigger up to central Au+Au • Offline: Match TPC tracks to triggered towers Andre Mischke (UU)

  32.  mass resolution and expected • STAR detector does not resolve individual states of the  - finite p resolution (B=0.5 T) - e-bremsstrahlung • Yield is extracted from combined ++ states • FWHM ≈ 700 MeV/c2  e+ e- NLO calculations R. Vogt et al., RHIC-II Heavy Flavor White Paper Andre Mischke (UU)

  33.  cross section and uncertainties Ldt = (5.6±0.8) pb-1 N = 48±15(stat.)  = geo×L0×L2×2(e)×mass Andre Mischke (UU)

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