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Explore the QCD Phase Diagram - Partonic Equation of State at RHIC

Explore the QCD Phase Diagram - Partonic Equation of State at RHIC Nu Xu Lawrence Berkeley National Laboratory Many Thanks to the Organizers. Outline. Introduction 2) STAR Experimental at RHIC 3) Partonic Collectivity in High-Energy Nuclear Collisions. Physics Goals at RHIC.

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Explore the QCD Phase Diagram - Partonic Equation of State at RHIC

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  1. Explore the QCD Phase Diagram - Partonic Equation of State at RHIC Nu XuLawrence Berkeley National Laboratory Many Thanks to the Organizers

  2. Outline • Introduction 2) STAR Experimental at RHIC 3) Partonic Collectivity in High-Energy Nuclear Collisions

  3. Physics Goals at RHIC • Identify and study the properties • of the matter (EOS) with partonic • degrees of freedom. • - Explore the QCD phase diagram. Hydrodynamic Flow Collectivity Local Thermalization = 

  4. STAR Experiment

  5. 1) Heavy-ion program - Study medium properties, EoS - pQCD in hot and dense medium 2) RHIC beam energy scan - Search for critical point - Chiral symmetry restoration STAR Physics Focus Polarized spin program - Study proton intrinsic properties Forward program - Study low-xproperties, search for CGC - Study elastic (inelastic) processes (pp2pp) - Investigate gluonicexchanges

  6. STAR Detector EMC barrel MRPC ToF barrel Ready for run 10 EMC End Cap RPSD FMS FPD TPC PMD Complete Ongoing DAQ1000 Ready for run 9 FTPC R&D Full azimuthal particle identification! e, π, ρ, K, K*, p, φ, Λ, Δ, Ξ, Ω, D, ΛC, J/ψ, Υ …

  7. STAR Detectors: Full 2π particle identification! EMC+EEMC+FMS (-1 ≤  ≤ 4) TPC TOF DAQ1000 HFT FGT

  8. Particle Identification at STAR TPC ToF TPC STAR TPC K pd π e, μ STAR ToF Log10(p) STAR HFT STAR EMC Neutral particles Strange Jets Heavy Quark hyperons Hadrons

  9. Particle Identification (ii) Reconstruct particles in full azimuthal acceptance of STAR!

  10. ud ss uud sss Hadron Spectra from RHICp+p and Au+Au collisions at 200 GeV 0-5% more central collisions Multi-strange hadron spectra are exponential in their shapes. STAR white papers - Nucl. Phys. A757, 102(2005).

  11. STAR: PRL. 99(2007)112301 Phys. Rev. Lett. 98, 62301(2007) - mesons and Strange Baryons ssbar fusion -meson formation! STAR: Phys. Lett. B612, 81(2005)

  12. The s-and d-quark Spectra Assuming that the processes of hadronization follow coalescence  - parton spectra - ‘partonic collective flow’ velocity ~ 0.35-0.45 c JinHui Chen: SQM08 c.f. Phys. Rev. C78 (2008) 034907

  13. STAR Detector MTD EMC barrel MRPC ToF barrel Ready for run 10 EMC End Cap RPSD FMS FPD TPC PMD Complete Ongoing DAQ1000 Ready for run 9 HFT FGT R&D

  14. Higgs mass: electro-weak symmetry breaking. (current quark mass) • QCD mass: Chiral symmetry breaking. (constituent quark mass) • New mass scale compared to the excitation of the system. • Important tool for studying properties of the hot/dense medium at RHIC. • Test pQCD predictions at RHIC. Quark Masses Total quark mass (MeV)

  15. Charm Hadron v2 • 200 GeV Au+Aum.b. • collisions (500M events). • - Charm hadron collectivity  • drag/diffusion constants  • medium properties! • 200 GeV Au+Aum.b. • collisions (|y|<0.5 500M events) • Charm hadron RAA • energy loss mechanism, e.g. • collisionalvs. radiative!

  16. PRL (07) • 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 • - High mass region: • J/e-e+ • minve-e+ • Direct radiation Expanding partonic matter at RHIC and LHC! Direct Radiation

  17. Pressure, Flow, … • tds = dU + pdV s– entropy; p – pressure; U – internal energy; V – volume t= kBT, thermal energy per dof • In high-energy nuclear collisions, interaction among constituents and density distribution will lead to: • pressure gradient  collective flow number of degrees of freedom (dof) • Equation of State (EOS) • No thermalization is needed – pressure gradient only depends on thedensity gradient and interactions. Space-time-momentum correlations!

  18. Anisotropy Parameter v2 coordinate-space-anisotropy  momentum-space-anisotropy y py px x Initial/final conditions, EoS, degrees of freedom

  19. Transverse Flow Observables 1) Radial flow – integrated over whole history of the evolution 2) Directed flow (v1) – relatively early 3) Elliptic flow (v2) – relatively early - Mass dependent: characteristic of hydrodynamic behavior.

  20. v2 at Low pT Region P. Huovinen, private communications, 2004 • Minimum bias data! • At low pT, model result fits mass hierarchy well - Collective motion at RHIC • - More work needed to fix the details in the model calculations.

  21. Collectivity, Deconfinement at RHIC - v2 of light hadrons and multi-strange hadrons - scaling by the number of quarks At RHIC: Nqscaling novel hadronization process • Parton flow • De-confinement • PHENIX: PRL91, 182301(03) • STAR: PRL92, 052302(04), 95, 122301(05) • nucl-ex/0405022, QM05 • S. Voloshin, NPA715, 379(03) • Models: Greco et al, PRC68, 034904(03) • Chen, Ko, nucl-th/0602025 • Nonaka et al. PLB583, 73(04) • X. Dong, et al., Phys. Lett. B597, 328(04). • …. i ii

  22.  -meson Flow: Partonic Flow “-mesons are produced via coalescence of seemingly thermalized quarks in central Au+Au collisions. This observation implies hot and dense matter with partonic collectivity has been formed at RHIC” STAR: Phys. Rev. Lett. 99 (2007) 112301// * STAR, Duke, TAMU ** OZI rule

  23. Centrality Dependence STAR: Phys. Rev. C77, 54901(2008) 200 GeV Au+Au S. Voloshin, A. Poskanzer, PL B474, 27(00). D. Teaney, et. al., nucl-th/0110037 • Larger v2/part indicates stronger flow in more central collisions. • NO partscaling. • The observed nq-scaling does not necessarily mean thermalization.

  24. Assuming that σ is same for all hadrons Note: only extract the product K0σcs K0 = 0.7 and cs2 = 1/3 (fixed) S is estimated from Glauber MC simulation K0value is determined so as to reproduce the transport model calculation (K0 = 0.7 ± 0.03)* *C. Gombeaud and J.-Y. Ollitrault, PRC77, 054904 (2008) Knudsen Fit σ : partonic cross section cs : speed of sound S : transverse area

  25. Ideal hydro v2/ε - εfrom“optical”Glaubermodel Simultaneous fits Note: Fit v2{4} and v2{ZDC-SMD} for charged hadrons not plotted here PHENIX π, K and p: preliminary, nucl-ex/0604011v1 STAR K0S, Λ, Ξ : Phys. Rev. C77, 054901 (2008) STAR φ : Phys. Rev. Lett. 99, 112301 (2007) Ideal Hydro. : P. Huovinen and P. V. Ruuskanen, Annu. Rev. Nucl. Part. Sci. 56, 163 (2006) and private communication Centrality Dependence of 〈v2〉

  26. Ideal Hydrodynamic Limit Drescher, Dumitru, Gombeaud, J.Ollitrault; Phys. Rev. C76, 024905 (2007) v2 max • - Only approaching hydro limit at most central collisions! • Questions: • Viscous effects ?? or Non-thermalization in HI collisions ??

  27. In 200 GeV Au+Au collisions at RHIC, strongly interacting matter formed: - Jet energy loss: RAA - Strong collectivity: v0, v1, v2 - Hadronization via coalescence: nq-scaling Questions: Has the thermalization reached at RHIC? - Serious analysis with dN/dpT and dv2/dpT results… - Heavy quark measurements When (at which energy) does this transition happen? What does the QCD phase diagram look like? -RHIC Beam Energy Scan sQGPand the QCD Phase Diagram

  28. The QCD Critical Point - LGT prediction on the transition temperature TC is robust. - LGT calculation, universality, and models hinted the existence of the critical point on the QCD phase diagram* at finite baryon chemical potential. - Experimental evidence for either the critical point or 1st order transition is important for our knowledge of the QCD phase diagram*. * Thermalization has been assumed M. Stephanov, K. Rajagopal, and E. Shuryak, PRL 81, 4816(98) K. Rajagopal, PR D61, 105017 (00) http://www.er.doe.gov/np/nsac/docs/Nuclear-Science.Low-Res.pdf 2010: RHIC Beam Energy Scan 2011: Heavy Quark measurements

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