Nu Xu“Hot and Dense Matter in the RHIC-LHC Era”, Mumbai, India, February 12-14, 20081/27 Many Thanks to the Conference Organizers Partonic EoS at RHIC Nu Xu Nuclear Science Division Lawrence Berkeley National Laboratory Many Thanks to the Conference Organizers

Nu Xu“Hot and Dense Matter in the RHIC-LHC Era”, Mumbai, India, February 12-14, 20082/27 Outline 1)Introduction 2) Hadron Spectra 3) Event anisotropy 4) Summary and outlook

Nu Xu“Hot and Dense Matter in the RHIC-LHC Era”, Mumbai, India, February 12-14, 20083/27 Identify and study the properties of matter (EoS) with partonic degrees of freedom and determine the QCD phase diagram. Penetrating probes Bulk probes - direct photons, leptons - spectra, v 1, v 2 … - “jets” and heavy flavor - partonic collectivity - fluctuations Physical Goals at RHIC Hydrodynamic Flow Collectivity Local Thermalization = 

Nu Xu“Hot and Dense Matter in the RHIC-LHC Era”, Mumbai, India, February 12-14, 20084/27 High-Energy Nuclear Collisions Initial Condition - initial scatterings - baryon transfer - E T production - parton dof System Evolves - parton interaction - parton/hadron expansion Bulk Freeze-out - hadron dof - interactions stop jets, leptons J/  D      K, K*  p  d, HBT elliptic flow v 2 radial flow  T Q2Q2 time T C T ch T fo partonic scatterings? early thermalization?

Nu Xu“Hot and Dense Matter in the RHIC-LHC Era”, Mumbai, India, February 12-14, 20085/27 Hadron Spectra from RHIC p+p and Au+Au collisions at 200 GeV sss ss uud ud Multi-strange hadron spectra are exponential in their shapes. STAR white papers - Nucl. Phys. A757, 102(2005). more central collisions 0-5%

Nu Xu“Hot and Dense Matter in the RHIC-LHC Era”, Mumbai, India, February 12-14, 20086/27 Thermal Model Fits (Blast-Wave) Source is assumed to be: –Locally thermal equilibrated –Boosted in radial direction random boosted E.Schnedermann, J.Sollfrank, and U.Heinz, Phys. Rev. C48, 2462(1993) Extract thermal temperature T fo and velocity parameter  T 

Nu Xu“Hot and Dense Matter in the RHIC-LHC Era”, Mumbai, India, February 12-14, 20087/27 Blast Wave Fits: T fo vs.    1) , K, and p change smoothly from peripheral smoothly from peripheral to central collisions. to central collisions. 2) At the most central collisions,  T  reaches collisions,  T  reaches 0.6c. 0.6c. 3) Multi-strange particles ,  are found at higher T fo  are found at higher T fo and lower  T  and lower  T   light hadrons move  light hadrons move with higher velocity with higher velocity compared to strange compared to strange hadrons hadrons STAR: NPA715, 458c(03); PRL 92, (04); 92, (04). 200GeV Au + Au collisions

Nu Xu“Hot and Dense Matter in the RHIC-LHC Era”, Mumbai, India, February 12-14, 20088/27 Compare with Model Results Hydro model works well for , K, p, but over-predicts flow for multi- strange hadrons Initial ‘collective kick’ introduced (P. Kolb and R. Rapp, PRC67)

Nu Xu“Hot and Dense Matter in the RHIC-LHC Era”, Mumbai, India, February 12-14, 20089/27 Slope Parameter Systematics Partonic expansion!

Nu Xu“Hot and Dense Matter in the RHIC-LHC Era”, Mumbai, India, February 12-14, /27 Direct Radiation from the Matter Expanding partonic matter at RHIC and LHC! PRL (07) SPS energy

Nu Xu“Hot and Dense Matter in the RHIC-LHC Era”, Mumbai, India, February 12-14, /27 Low-mass Dileptons 1)At s~1 GeV 2, 2  channel strength drop 2)Measured vector   +  - (e + e - ), but axial vector?  Related to the collective expanding? ALEPH data: Vacuum

Nu Xu“Hot and Dense Matter in the RHIC-LHC Era”, Mumbai, India, February 12-14, /27 Direct Radiation from the Matter Expanding partonic matter at RHIC and LHC! Di-leptons allow us to measure the direct radiation from the matter with partonic degrees of freedom, no hadronization! Puzzle 1: dramatic change of the slope parameter at m ~ 1 GeV 2 Puzzle 2: source of T at m ≥ 1.5 GeV 2 RHIC & LHC: T will increase with mass!

Nu Xu“Hot and Dense Matter in the RHIC-LHC Era”, Mumbai, India, February 12-14, /27 Summary I 1) Multi-strange hadrons and heavy quark hadrons freeze-out early 2) At RHIC, mass > 1 GeV 2, partonic interactions dominate. Interactions of ,  N are important for mass < 1 GeV 2.

Nu Xu“Hot and Dense Matter in the RHIC-LHC Era”, Mumbai, India, February 12-14, /27 y x pypy pxpx coordinate-space-anisotropy  momentum-space-anisotropy Anisotropy Parameter v 2 Initial/final conditions, EoS, degrees of freedom

Nu Xu“Hot and Dense Matter in the RHIC-LHC Era”, Mumbai, India, February 12-14, /27 v 2 - Identified Particles at High p T QM08 : S. Huang ; M. Issah pions PHENIX results from their new MRPC-TOF and RP detectors! Extended to higher p T region! The more central the collision, the smaller the v 2 kaons protons

Nu Xu“Hot and Dense Matter in the RHIC-LHC Era”, Mumbai, India, February 12-14, /27 v 2 - High p T - n q Scaling 1) Scaling observed at both centralities. 2) KE T scaling seems break down for KE T /n q > 1 GeV/c 2 in peripheral collisions - non-flow effects QM08 : S. Huang ; M. Issah

Nu Xu“Hot and Dense Matter in the RHIC-LHC Era”, Mumbai, India, February 12-14, /27 Collectivity, Deconfinement at RHIC - v 2 of light hadrons and multi-strange hadrons - scaling by the number of quarks At RHIC:  m T - NQ scaling  De-confinement PHENIX: PRL91, (03) STAR: PRL92, (04), 95, (05) nucl-ex/ , QM05 S. Voloshin, NPA715, 379(03) Models: Greco et al, PRC68, (03) Chen, Ko, nucl-th/ Nonaka et al. PLB583, 73(04) X. Dong, et al., Phys. Lett. B597, 328(04). …. i ii

Nu Xu“Hot and Dense Matter in the RHIC-LHC Era”, Mumbai, India, February 12-14, /27  -meson v 2 : Partonic Collectivity “  -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” QM08 : J. Chen; X.B. Wang

Nu Xu“Hot and Dense Matter in the RHIC-LHC Era”, Mumbai, India, February 12-14, /27 Centrality Dependence of PID v 2  All centralities: mass ordering at low p T  m T -m scaling at low m T -m.  All centralities: baryon v 2 > meson v 2 at intermediate p T and m T -m.  Hydrodynamic model predictions do not show the scaling behavior. Non-viscous hydro: P. Huovinen, private communications, 07/ / STAR data: arXiv: v1 QM08: Y. Lu; S Dash

Nu Xu“Hot and Dense Matter in the RHIC-LHC Era”, Mumbai, India, February 12-14, /27 Eccentricity Scaling(?) STAR: arXiv: v1  Larger v 2 /  part indicates stronger flow in more central collisions.  The observed n q -scaling does not necessarily mean thermalization. 200 GeV Au+Au QM08: Y. Lu ; S Dash S. Voloshin, A. Poskanzer, PL B474, 27(00). D. Teaney, et. al., nucl-th/

Nu Xu“Hot and Dense Matter in the RHIC-LHC Era”, Mumbai, India, February 12-14, /27 (no) Scaling in Hydro Model 1)No scaling is observed in the non-viscous hydrodynamic model predictions. 2)Realistic calculations with viscosity are necessary! - STAR data: PRC 72, , 2005 arXiv: v1 - Non-viscous hydrodynamic results: P. Huovinen, private communications D. Teaney, J. Lauret, and E.Shuryak, nucl-th/ T. Hirano et al. Phy. Lett. B636, 299 (06); J. Phys. G34 S879(07); arXiv:

Nu Xu“Hot and Dense Matter in the RHIC-LHC Era”, Mumbai, India, February 12-14, /27 Summary II 1) Partonic interactions are responsible to early collectivity  Partonic Collectivity at RHIC. 2) More sophisticated, serious model calculations, including proper initial condition, viscosity, … are needed.

Nu Xu“Hot and Dense Matter in the RHIC-LHC Era”, Mumbai, India, February 12-14, /27 Quark Masses 1)Higgs mass: electro-weak symmetry breaking. (current quark mass) 2)QCD mass: Chiral symmetry breaking. (constituent quark mass) éNew mass scale compared to the excitation of the system. éImportant tool for studying properties of the hot/dense medium at RHIC. éTest pQCD predictions at RHIC. Total quark mass (MeV)

Nu Xu“Hot and Dense Matter in the RHIC-LHC Era”, Mumbai, India, February 12-14, /27 New Results on Non-photonic e v 2 1) Heavy quark collectivity => light quark thermalization! Muller nucl-th/ ) Non-photonic electron v 2 indicates non-zero v 2 of Charm-hadrons. 3) Large systematic errors. Need directly reconstructed heavy quark-hadrons!! PHENIX run-IV: PRL, 98, (2007) QM08: R. Averbeck; A. Dion

Nu Xu“Hot and Dense Matter in the RHIC-LHC Era”, Mumbai, India, February 12-14, /27 STAR Detector MRPC ToF barrel RPSD PMD F0SF0S FMSFMS EMC barrel EMC End Cap - DAQ TPC FEE - MTD - Soft  HFT: Si-pixels; IST: Si-strips; FGT: GEM-layers Integrated Tracking Upgrades finished ongoing MTD

Nu Xu“Hot and Dense Matter in the RHIC-LHC Era”, Mumbai, India, February 12-14, /27 Charm Hadron v GeV Au+Au minimum biased collisions (500M events). - Charm collectivity  drag/diffusion constants  medium properties! D 0, D ±, D *,D s  C Bottom-hadrons Charm background At low mass region

Nu Xu“Hot and Dense Matter in the RHIC-LHC Era”, Mumbai, India, February 12-14, /27 Summary Physics Today L. McLerran, T. Ludlam, Hot and dense system created in Au+Au collisions At RHIC Spectra: At RHIC, mass > 1 GeV 2, partonic interactions dominate. Anisotropy v 2 : Partonic interactions are responsible to early collectivity at RHIC. More sophisticated, serious model calculations are needed. Next Step: Test thermalization of light-quark by studying the heavy-quark collectivity.