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Search for Quark-Gluon Plasma at RHIC

Search for Quark-Gluon Plasma at RHIC. Byungsik Hong Korea University. Relativistic Heavy-Ion Collisions. Approaching v > 0.9c. Collisions. Passing through. Expansion. Some of beam energy they had before is transformed into heat and new particles right here ! . T(MeV). Early Universe

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Search for Quark-Gluon Plasma at RHIC

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  1. Search for Quark-Gluon Plasma at RHIC Byungsik Hong Korea University

  2. Relativistic Heavy-Ion Collisions Approaching v > 0.9c Collisions Passing through Expansion Some of beam energy they had before is transformed into heat and new particles right here ! Hanyang University

  3. T(MeV) Early Universe (RHIC) Quark-Gluon Plasma RHIC & future LHC explore high temperature & low baryon density partonic matter. ~150 Phase Transition Color Superconductor Neutron Star Hadron Gas SIS explores high baryon density hadronic matter. Atomic Nuclei ~10 Density(n0) Nuclear Phase Diagram Hanyang University

  4. Relativistic Heavy-Ion Accelerators Hanyang University

  5. Brookhaven National Lab. in New York • Circumference: 3.83 km • First collision: 2000 • 100A GeV Au+Au(2X1026/cm2/s) • 250 GeV p + p (2X1032/cm2/s) Relativistic Heavy Ion Collider PHENIX STAR Hanyang University

  6. More about the PHENIX PHENIX= Pioneering High Energy Nuclear Interaction eXperiment Hanyang University

  7. The STAR Detector STAR=Solenoid Tracker at RHIC Magnet Coils Central Trigger Barrel (CTB) ZCal Time Projection Chamber (TPC) Year 2000 Barrel EM Cal (BEMC) Silicon Vertex Tracker (SVT)Silicon Strip Detector (SSD)mVertex Detector FTPCEndcap EM CalFPD TOFp, TOFrYear 2001/2003 Year 2006+ Hanyang University

  8. Outline • Collective flow • HBT • High pt hadron suppression • Jet quenching • Summary of the Quark Matter 04 Conference 3D imaging of the hot fireball See more deep inside Hanyang University

  9. transverse plane (at midrapidity) reaction plane time v1<0 v1 >0 sideward flow px = v1 pt v2<0 v2 >0 elliptic flow RN=(1+ v2)/(1-v2) Collective Flow Reaction plane Fourier expansion of azimuthal distribution gives the phase space distribution w.r.t. the reaction plane. S. Voloshin & Y. Zhang, Z. Phys. C70, 665 (1996) J.Y. Ollitrault, Nucl. Phys. A638, 195c (1998) Hanyang University

  10. x z η∼0 η∼3 η∼-3 Anisotropic Flowv1, v2, v4, … h~3 h~-3 h~0 Reaction plane Spectators Spectators v2 = 15% v2 = 15%, v4=4% 1.5 Y 1 Out-of-plane 0.5 In-plane X v2 = 7% v2 = 7%, v1=+7% v2 = 7% v2 = 7%, v1=-7% Hanyang University Isotropic emission

  11. Directed Flow v1 • Consistent among RHIC Expts. • Shape in forward rapidity agree with low energy data by NA49 • Elongated shape near midrapidity STAR, PRL92, 062301 (2004) NA49, PRC69, 034903 (2003) M. Belt-Tonjes for PHOBOS (QM04) H. Masui for PHENIX (QM04) Hanyang University PHENIX preliminary Poster by Hiroshi Masui

  12. v2 vs Rapidity STAR M.B. Tonjes for PHOBOS (QM04) v2 is positive: v1 and v2 are in the same plane Hanyang University

  13. STAR Preliminary v2 vs pt including strangeness Scaled with the number of quarks except π± This saturation can be explained by the surface emission due to the dense & opaque medium, Shuryak, PRC 66, 027902 (2002) Quark coalescence at RHIC? D. Molnar and S.A. Voloshin, PRL 91, 092301(2003) Critical test by pentaquark with n=5 STAR, PRL92, 052302 (2004) Hanyang University

  14. Rlong p1 qside x1 p2 qout Rside qlong x2 Rout 2 C (q) Gaussian model (3-d): 1 Final-state effects (Coulomb, strong) also need to be accounted for. q (GeV/c) HBT interferometry • Two-particle interferometry: p-space separation  space-time separation Hanyang University

  15. kT-dependence Agree among RHIC expts. HBT Excitation Function of π STAR, PRL 87, 082301 (2001) Hanyang University

  16. beam into screen hydrodynamic expansion late rescattering time  Initial geometry →aniosotropies in pressure gradients  Preferential in-plane expansion →decreases spatial anisotropy  Freeze-out source shape → model dependentmeasure of pressure, expansion time Azimuthally Sensitive π HBT • Probes spatial anisotropy at freeze-outWiedemann, PRC57, 266 (1998) • Freeze-out shape probes nature & timescale of system evolution • How much initial spatial deformation survives system expansion? Hanyang University

  17. qlong qside qout reactionplane Azimuthally sensitive πHBT Rside2  = 90° Rside (small) Rside (large)  = 0° Hanyang University

  18. Au+Au, √s = 200 GeV HBT(): Centrality & kT dependence STAR, nucl-ex/0312009 Hanyang University

  19. System deformation at Freeze-out • Final state eccentricity from • v2 • HBT with respect to the reaction plane b t Hanyang University

  20. q q Nuclear Modifications to Hard Scattering PHENIX, PRL91, 072301 (2003); 88, 022031 (2002) • Large Cronin effect at low energy • Large suppression at RHIC (jet quenching) • Is the suppression due to the medium (Initial or final state effect)? Hanyang University

  21. Proton/deuteron -nucleus collision Nucleus -nucleus collision d+Au Control Experiment • Collisions of small with large nuclei were always foreseen as necessary to quantify cold nuclear matter effects. • Recent theoretical work on the “Color Glass Condensate” model provides alternative explanation of data: • Jets are not quenched, but are a priori made in fewer numbers. • Kharzeev, Levin, & Nardi, NPA730, 448 (2004) • Small + Large distinguishes all initial and final state effects. VS Hanyang University

  22. Initial State Effects Only d+Au Initial + Final State Effects Au+Au RAA vs RdA for Identified p0 d-Au results rule out CGC as the explanation for jet suppression at central rapidity and high pT Hanyang University

  23. Cronin Effect: Multiple Collisions broaden high PT spectrum Charged Hadron Results • Striking difference of d+Au and Au+Au results. • Charged Hadrons higher than neutral pions. Hanyang University

  24. Centrality Dependence Au + Au Experiment d + Au Control Experiment • Dramatically different and opposite centrality evolution of Au+Au experiment from d+Au control one. • Jet Suppression is clearly a final state effect. PHENIX, PRL91, 072303 (2003) Final Data Preliminary Data Hanyang University

  25. Rcp Variable STAR, PRL92, 052303 (2004) Rcp=binary-collision scaled centrality ratio This suppression can be explained by the parton energy loss due to the dense & opaque medium, Gyulassy & Wang, NPB 420, 583 (1994) Mesons and baryons show different behaviors.  Dependence on the number of valence quarks  Support the quark coalescence again Hanyang University

  26. “Trigger”  = 0 away-side near-side trigger Jet Quenching;Azimuthal dependence • 2-Particle Correlations: dN/d() STAR, PRL90, 082302 (2003) Hanyang University

  27. Disappearance of the Away-Side Jet STAR, PRL91, 072304 (2003); 90, 082302 (2003) Background subtracted 1/NtriggerdN/d() di-hadron ppdAuAuAu Near side jet “identical” p+p: 2 jets d+Au: 2 jets Au+Au peripheral 2 jets Au+Au central 1 jet ! Hanyang University

  28. Out-of-plane In-plane Measured Reflected Path Length Dependence di-hadron, 20 - 60% central STAR Preliminary Suppression is larger in out-of-plane (longer path length) ! Hanyang University

  29. Path Length Dependence di-hadron, 20-40% Central Out-of-plane In-plane Jet quenching is consistent with path length dependence ! Hanyang University

  30. Particle Dependence of Asymmetry Associated Mesons PHENIX Preliminary Associated Baryons Noticeable differences in the asymmetries for associated baryons and mesons Hanyang University

  31. Conclusions • Flow • A wealth of hadron data becomes available for v1, v2 (even v4 and v6 from STAR). • Electron and charm flows from PHENIX • HBT • Out-of-plane extended source at freeze-out • Short lived system remembers its initial spatial geometry • Jet Quenching • Cronin in d+Au • Suppression/non-suppression follow baryon/meson line (not mass): more suppression for mesons. • Away-side jet quenching in central Au+Au • Azimuthal dependence consistent with the path length dependence by HBT Hanyang University

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