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Bulk Properties of QCD – matter at Highest Colider Energies

Bulk Properties of QCD – matter at Highest Colider Energies. Kai Schweda, University of Heidelberg / GSI Darmstadt. QCD Phase Diagram. Outline. Identify and study QCD bulk-matter with partonic degrees of freedom: Gobal observable - multiplicity Chemical freeze-out, T ch and m B

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Bulk Properties of QCD – matter at Highest Colider Energies

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  1. Bulk Properties of QCD – matter at Highest Colider Energies Kai Schweda, University of Heidelberg / GSI Darmstadt

  2. QCD Phase Diagram

  3. Outline • Identify and study QCD bulk-matter with partonic degrees of freedom: • Gobal observable - multiplicity • Chemical freeze-out, Tch and mB • Partonic collectivity, Tfo and bT • Heavy – quark collectivity • Summary

  4. Mid - rapidity Densities PHOBOS fit HIJING BBar Armesto et al. AMPT Eskola CGC KLN ASW DPMJET-III EHNRR • at LHC, dN/dh 1000 - 3000 • estimate energy density PHOBOS compilation: W. Busza, SQM07. Theory points: HI at LHC – last call for predictions, CERN, May 2007.

  5. EoS from Lattice QCD • 1) Large increase in  ! • Large increase in Ndof: Hadrons vs. partons 2) TC~ 160 MeV 3) Boxes indicate max. initial temperatures • Longest expansion duration at LHC • Expect large partonic collectivity at LHC SPS RHIC LHC ? Z. Fodor et al, JHEP 0203:014(02) C.R. Allton et al, hep-lat/0204010 F. Karsch, Nucl. Phys. A698, 199c(02).

  6. Chemical Freeze - out

  7. Hadron Yield - Ratios 1) At RHIC: Tch = 160 ± 10 MeV B = 25 ± 5 MeV 2) S= 1.  The hadronic system is thermalized at RHIC. 3)Short-lived resonances show deviations.  There is life after chemical freeze-out. RHIC white papers - 2005, Nucl. Phys. A757, STAR: p102; PHENIX: p184; Statistical Model calculations: P. Braun-Munzinger et al. nucl-th/0304013.

  8. Chemical Freeze-Out vs Energy • With increasing energy: • Tch increases and saturatesat Tch = 160 MeV • Coincides with Hagedorn temperature • Coincides with early lattice results limiting temperature for hadrons, Tch 160 MeV ! • mB decreases, mB = 1MeV at LHC •  Nearly net-baryon free ! A. Andronic et al., NPA 772 (2006) 167.

  9. Baryon Ratios • With increasing energy: • Baryon ratios approach unity • At LHC, pbar / p  0.95 challenge, need 1% precision to address net-baryon transport ! Compilation: N. Xu

  10. Partonic Collectivity

  11. Elliptic Flow • “Elliptic flow is larger for pions but smaller for protons at LHC than at RHIC”. • This is expected from simple, hydro-like blast-wave fits ! • larger collective flow: mass ordering more pronounced ! Theory points: C.M. Ko – last call for predictions, CERN, May 2007.

  12. Collectivity - Energy Dependence • Collectivity parameters <bT> and <v2> increase with energy • Two extreme secenarios:(a) Tfo Tch AND bT 0.8 pure partonic collectivity at LHC! (b)Tfo Tch , bT 0.3 no collectivity, no QGP !

  13. Higgs mass: electro-weak symmetry breaking. (current quark mass) • QCD mass: Chiral symmetry breaking. (constituent quark mass) • Strong interactions do not affect heavy-quark masses. • Important tool for studying properties of the hot/dense medium at RHIC and LHC. • Test pQCD predictions at RHIC and LHC. Quark Masses Total quark mass (MeV) X. Zhu, M. Bleicher, K.S., H. Stoecker, N. Xu et al., PLB 647 (2007) 366.

  14. Charm Correlations c-cbar are correlated • Pair creation: back to back • Gluon splitting: forward • Flavor excitation: flat Correlations vanish  frequent interactions among partons !  probe light-quark thermalization ! Pythia calcs.: G. Tsiledakis.

  15. Hadronic Re-scattering • Hadronic re-scattering can not completely wash out DD-correlations • Frequent partonic re-scattering needed  light quark thermalization ! X. Zhu, M. Bleicher, K.S., H. Stoecker, N. Xu et al., PLB 647 (2007) 366.

  16. J/y Production P. Braun-Munzinger and J. Stachel, Nature 448 (2007) 302.  suppression,compared to scaled p+p  regeneration,enhancement (SPS) Low energy (SPS): few ccbar quarks in the system  suppression of J/y High energy (LHC): many ccbar pairs in the system  enhancement of J/y  Signal of de-confinement + thermalization of light quarks !

  17. Predictions for LHC • large ccbar production at LHC • corona effects negligible • regeneration of J/y dominates • striking centrality dependence Signature for QGP formation ! • Initial conditions at LHC ? scc A. Andonic et al., nucl-th/0701079.

  18. x1000 Multiply Heavy-flavored Hadrons • Statistical hadronization- de-confined heavy-quarks • equilibrated heavy-quarks •  Enhancement up to x1000 ! • Measure Xcc, Wcc, Bc, (Wccc) • Need total charm yields • Probe deconfinement and thermalization @ LHC • QGP ! Quarks and gluons  hadrons Pb+Pb Wccc / D : p+p c c c F. Becattini, Phys. Rev. Lett. 95, 022301 (2005); P. Braun-Munzinger, K. Redlich, and J. Stachel, nucl-th/0304013.

  19. Heavy - Quark Production • Charm x 10 • Beauty x 100 • 3) Heavy-quarks abundantly produced at LHC ! STAR data: A. Suaide, P. Djawothoto QM2006;Calcs.: R. Vogt.

  20. ATLAS CMS • Low – momentum • CMS/ATLAS: Si only tracking • CMS: pT > 0.150 GeV • ALICE: large momentum coverage in full azimuth • address bulk properties ! • characterize Quark Gluon Plasma ! Mid - Rapidity Performance CMS: TDR.v2, CERN-LHCC-2007-009; ATLAS: B. Cole, SQM2007; ALICE: PPR.vol.II, J. Phys. G 32 (2006) 1295.

  21. J/y  e+ + e- Reconstruction J/y: c c : b b • J/y e+ + e- • identify electrons through their transition radiation  Precise Measurement of Quarkonia !

  22. D - Meson Performance • Measure secondary vertex  Direct reconstruction of D0 precise measurement of total heavy-quark yield address heavy – quark collectivity ! ALICE: PPR.vol.II, J. Phys. G 32 (2006) 1295.

  23. Summary • Bulk properties at LHC:dN / dh 1000 – 3000Tch 160 ± 10 MeV, mB  0 – 5 MeVTfo Tch all collectivity from partonic stage<bT> = 0.8 ± 0.05 (c), <v2>  0.08 • Measure spectra, correlations and v2 of:D0, D+, Ds, J/y, Lb,to identify and characterize QGP ! • ALICE is well suited for these studies

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