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ICPAQGP 2010, Goa, India High-Energy Nuclear Collisions and QCD Phase Structure Nu Xu (1) Nuclear Science Division, Lawrence Berkeley National Laboratory, USA (2) College of Physical Science & Technology, Center China Normal University, China. Outline. Introduction: Phase Structure of QCD

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Outline

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  1. ICPAQGP 2010, Goa, IndiaHigh-Energy Nuclear Collisions and QCD Phase StructureNu Xu(1) Nuclear Science Division, Lawrence Berkeley National Laboratory, USA(2) College of Physical Science & Technology, Center China Normal University, China

  2. Outline Introduction: Phase Structure of QCD RHIC beam energy scan: v2, χp Phase diagrams of QCD: a collection

  3. Quantum ChromoDynamics S L QCD is the basic theory for strong interaction. Its degrees of freedom, are well defined at small distance. Little is known regarding the dynamical structures of matter that made from q, g. E.g. theconfinement, nucleon spin, the QCD phase structure... Large αS and strong coupling – QCD at long distance.

  4. Beam Energy Scans at RHIC and LHC Chemical freeze-out (tri-)Critical point LHC: 2.76 – 5.4 TeV (Pb) (0.9 – 14 TeV (p)) RHIC: 200 – 5 GeV (Au) FAiR*/NICA: 11 – 4 GeV (Au) T: 180 – 55 MeV μB: 5 – 800 MeV

  5. (2) RHIC Beam Energy Scan

  6. STAR’s BES Plan* As low the beam energy as possible in order to cover a wide range. Marches to corresponding SPS center of mass energy. Started in Run10 when the new TOF was ready. * Phase-I. Depends on the out comes, we may have Phase-II BES at more focused region of the beam energy scan

  7. STAR Detector EMC Barrel MRPC ToFBarrel HLT BBC TPC FTPC PMD Fast DAQ and particle identification over 2p in azimuthal angle in a wide rapidity window.

  8. Centrality Determinations Mid-ydN/dη collision centrality Npart, εstd, εpart. Understand the initial condition is essential!

  9. Particle Identification √sNN = 39 GeV Au + Au Collisions TPCTPC+ToF

  10. PID: 7.7, 39, 200 GeV (π±, K±, p) Au+Au at 7.7 GeV Au+Au at 39 GeV Au+Au at 200 GeV

  11. High Moments: Critical Point Search • Measure conserved quantities, B, s,and Q. • First: High order fluctuation results consistent with thermalization. • First: Tests the long distance QCD predictions in hot/dense medium. • Caveats: (a) static vs. dynamic; (b) net-B vs. net-p; (c) potential effects of freeze-out… • R. Gavai, S. Gupta, 1001. 3796 / F. Karsch, K. Redlich, 1007.2581 / M. Stephanov, 0911.1772. • STAR: PRL105, 02232(2010) and references therein.

  12. Partonic Collectivity at RHIC STAR: preliminary QM09: arXiv 0907.2265 Partonic Collectivity at RHIC! Session-7: Shi // arXiv 0907.2265 // PHENIX: nucl-ex/0604011

  13. Number of Quark Scaling in v2 • At intermediate pT region, v2-scaling in nq works for π, K, ρ0, p, ϕ, Λ, Ξ, Ωand light nuclei up to 3He. • Coalescence process for hadronization. • Partonic collectivity and de-confinement. [STAR Jena: ICPAQGP10] v2/nq [STAR Shi: ICPAQGP10]

  14. Observable: Quark Scaling  • m ~ mp ~ 1 GeV • ss not K+K- • h<< p,  • In the hadronic case: • No number of quark scaling • Very small value of v2 !

  15. Results on Anisotropic Flow ALICE arXie1011.3914 From Kuma, Mohanty and Shi Stronger collectivity at LHC! Initial eccentricity ε is largely uncertain

  16. Energy Dependence: K/pRatio • N(K+)/N(p+) ratio vs. √sNNmay reflect the degree of baryon stopping, due to the associate process: NN NΛK+. Important for strangeness production! • √sNN~ 8 GeV is the max. of freeze-out baryon density. J. Randrup & J. Cleymans, Phys. Rev. C 74 (2006) 047901 √sNN~8 GeV [Kumar: ICPAQGP2010]

  17. Other Observables At each collision energy: Local parity violation: a three particle correlation measurement HBT as a function of reaction plane Directed flow v1 E-by-E N(K)/N(p), N(p)/N(p) ratios E-by-E <pT>, <Nch> High moments for net-charge, p, K, p

  18. (3) Collection ofQCD Phase Diagram

  19. QCD Phase Diagram (1953) RHIC Neutron stars Neutron stars Neutron stars E. Fermi: “Notes on Thermodynamics and Statistics ” (1953)

  20. QCD Phase Diagram 1983 (1, 2, 5-10)ρ0 1983 US Long Range Plan - by Gordon Baym TC~200 MeV (1, 2, 5-10)*ρ0

  21. QCD Phase Diagram (2009) 1983 US Long Range Plan - by Gordon Baym nucl-th: 0907.4489, NPA830,709(09) L. McLerran nucl-th 0911.4806: A. Andronic, D. Blaschke, P. Braun-Munzinger, J. Cleymans, K. Fukushima, L.D. McLerran, H. Oeschler, R.D. Pisarski, K. Redlich, C. Sasaki, H. Satz, and J. Stachel Systematic experimental measurements (Ebeam, A) : Extract numbers that is related to the QCD phase diagram!

  22. Slope Parameter Systematics Partonic Hadronic Student Lecture, “Quark Matter 2006”, Shanghai, Nov. 14 - 20, 2006

  23. Hadronic Partonic • Di-leptons allow us to measure the direct radiation from the matter with partonic degrees of freedom, no hadronization! • Low mass region: • , , e-e+ • minve-e+ • medium effect • Chiral symmetry(?) • -Intermediateregion: • J/e-e+ • minve-e+ • Direct radiation Expanding partonic matter at RHIC and LHC! Direct Radiation Measurements Direct radiation: hadronic partonic STAR already started its di-electron measurements!

  24. Di-lepton Program at STAR STAR Preliminary ω ϕ J/ψ pT (GeV/c) Key measurements: yields, mass, RAA, v2 thermalization, thermal rates

  25. γ*γ*Interferometry (HBT) Hadronic Partonic [Mohanty: ICAPQGP10] Virtual gamma HBT sensitive to, due to the off-shell mass, is sensitive to the duration of the source, hence the collectivity as a function of emission time. The di-leptons sense ‘volume emission’ while hadrons are mostly ‘surface emission’! Leptons: QGP evolution (phase) can be assessed. P. Mohanty, J. Alam, B. Monhanty,arXiv:1008.1111

  26. D-lepton Signal for QGP Expansion Hadronic Partonic Di-lepton transverse mass slope parameters reflect the sources. At the intermediate mass region (IMR), partonic phase is dominate, the slope parameter vary smoothly while dramatic effects are seen at the low mass region (M ≤ 1 GeV). J. Deng, Q. Wang, NX, PF. ZhuangarXiv:1009.3091

  27. Summary The QCD phase structure long distance QCD. A serious beam energy scan program, for the search of QCD critical point and phase boundary, has just began. Next generation of new experiments with high rate capabilities are important for the study of the QCD phase structure around the phase boundary. NA61 at SPS, CBM at FAiRand MPD at NICA. In order to understand the dynamical evolution from cold nuclear matter to quark gluon plasmain high-energy nuclear collisions, a good understanding of the initial condition is necessary.

  28. CPOD2011, Nov. 7-11, 2011 Wuhan, China (Critical Point and Onset of De-confinement) International Summer School for High-Energy Nuclear Physics* Nov. 1-5, 2011 Wuhan, China *Supported in part by HIC for FAiR

  29. Many Thanks to the Organizers!

  30. Phase Diagram QED QCD Phase Diagram: A map shows that, at given degrees of freedom, how matter organize itself under external conditions.

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