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Particle Production, Correlations, and Jet Quenching at RHIC *

Particle Production, Correlations, and Jet Quenching at RHIC *. John Harris Yale University. * Relativistic Heavy Ion Collider. quark-hadron phase transition 2 x 10 12 Kelvin. Early Universe. National Geographic (1994) & Michael Turner.

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Particle Production, Correlations, and Jet Quenching at RHIC *

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  1. Particle Production, Correlations, and Jet Quenching at RHIC* John Harris Yale University * Relativistic Heavy Ion Collider John Harris (Yale University) QCD@Work 2003, Bari, Italy

  2. quark-hadron phase transition 2 x 1012 Kelvin Early Universe National Geographic (1994) & Michael Turner John Harris (Yale University) QCD@Work 2003, Bari, Italy

  3. “In high-energy physics we have concentrated on experiments in which we distribute a higher and higher amount of energy into a region with smaller and smaller dimensions. In order to study the question of‘vacuum’, we must turn to a different direction; we should investigate some ‘bulk’ phenomena by distributing high energy over a relatively large volume.” T.D. Lee (Nobel Laureate) Rev. Mod. Phys. 47 (1975) 267. John Harris (Yale University) QCD@Work 2003, Bari, Italy

  4. Lattice QCD Calculations q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q John Harris (Yale University) QCD@Work 2003, Bari, Italy

  5. Purpose of Relativistic Heavy Ion Physics • Investigate High Density QCD Matter in Laboratory • Determine its properties • Phase Transitions? • Deconfinement to Quark-Gluon Plasma • Chiral symmetry restoration • Relevance? • Quark-hadron phase transition in early Universe • Cores of dense stars • High density QCD John Harris (Yale University) QCD@Work 2003, Bari, Italy

  6. Outline • Introduction • Relativistic Heavy Ion Collider • Particle Production and Correlations • Hard Scattering and Jet Quenching • Conclusions & Future Expectations John Harris (Yale University) QCD@Work 2003, Bari, Italy

  7. BRAHMS PHOBOS STAR PHENIX Relativistic Heavy Ion Collider RHIC John Harris (Yale University) QCD@Work 2003, Bari, Italy

  8. Au on Au Event at CM Energy ~ 130 A-GeV Central Event beam view side view color code energyloss John Harris (Yale University) QCD@Work 2003, Bari, Italy

  9. p e L m p K f jet g Freeze-out Hadronization QGP Hard Scattering + Thermalization Au Au Space-time Evolution of Collisions time g e  Expansion  space John Harris (Yale University) QCD@Work 2003, Bari, Italy

  10. Motivation for Particle Production and Correlations at RHIC • Thermalization? • Particle yields & ratios, strangeness  chemical equilibration (T, mB) • Spectra  thermal freezeout (Tfo) + collective flow (b) • Pressure gradients  particle & energy flow? • Particle Correlations  transverse (bT) & elliptic flow (v2) pressure • Timescales? • Bose-Einstein (HBT) Correlations  space-time evolution, system shape and size • Deconfinement? • Effects of medium on J/y, resonances, parton propagation John Harris (Yale University) QCD@Work 2003, Bari, Italy

  11. dNch/dh M. Baker (PHOBOS) QM2002 Au + Au at RHIC h = - ln [ tan(q/2)] Note - at least 7500 x 2  > 15,000 q + q in final state (also large number of gluons early) originally 3 quarks x 2 nuclei x 197 nucleons ~1200 valence quarks > 92% of (> 15,000) quarks in final state are produced Large Number of Produced Particles dnch/dh|h=0= 670 Ntotal ~ 7500 John Harris (Yale University) QCD@Work 2003, Bari, Italy

  12. dNch/dh STAR M. Baker (PHOBOS) QM2002 Longitudinal Flow (Bjorken expansion) Boost invariant - central rapidity plateau Boost-Invariance at Mid-rapidity John Harris (Yale University) QCD@Work 2003, Bari, Italy

  13. for Au+Au: R = 6.5 fm, pR2 ~ 130 fm2 dET/dh ~ 600 GeV <mT> dN/dy = 0.534 GeV (1150) dET/dh e  4.6 GeV/fm3/ t(t ~ 0.1–1)dn/dh e  4.3 GeV/fm3/ t PHENIX pR2 30 x nuclear density > 4 x ec Energy Densities at RHIC Longitudinal expansion – J.D. Bjorken, PRD27 (1983) 140. pR2 John Harris (Yale University) QCD@Work 2003, Bari, Italy

  14. General Particle Ratios  Chemical Equilibrium Statistical Model fits particle ratios for 200 GeV Au + Au: T = 177 MeV mB = 29 MeV John Harris (Yale University) QCD@Work 2003, Bari, Italy

  15. Y X f XZ-plane - the reaction plane Elliptic Flow – a Probe of Early Dynamics • Azimuthal anisotropyelliptic flow measures •  response of the system to early pressure • the system’s ability to convert original spatial • anisotropy into momentum anisotropy • sensitive to early dynamics of initial system v2: 2nd Fourier harmonic coefficient of azimuthal distribution of particles with respect to the reaction plane  measures elliptic flow John Harris QCD@Work 2003, Bari, Italy

  16. Au+Au at b=7 fm t = 8 fm/c t = 3.2 fm/c Contours of equal energy density t2 t3 t1 t4 y (fm) x (fm) Hydrodynamic Calculation of Elliptic Flow P. Kolb, J. Sollfrank, and U. Heinz John Harris QCD@Work 2003, Bari, Italy

  17. Charged Particle Elliptic Flow (v2) RG + QGP Resonance gas STAR Evidence that initial spatial asymmetry is efficiently translated into momentum space anisotropy (as in hydrodynamics) Increasing pressure gradients in the system STAR PRL87 (2001)182301 Mass dependence of V2(pT) sensitive probe of QCD EOS P (T) Rapid pressure buildup, explosive hydrodynamic expansion Hydrodynamics needs quark-gluon softening of the hadronic EOS P. Huovinen, P. Kolb, U. Heinz & indepedently D. Teaney et al. also CM Ko et al., M. Bleicher et al., J. Kapusta et al. John Harris QCD@Work 2003, Bari, Italy

  18. Characteristics of RHIC Collisions from Experiment Summary of Soft Physics from the > 40 refereed journal publications from RHIC experiments: global observations: Large produced particle multiplicities dnch/dh|h=0= 670, Ntotal ~ 7500 > 92% of (>15,000) quarks of final state are produced quarks Large energy densities (dn/dh, dET/dh) e  5 GeV/fm3/ t (t ~ 0.1–1) Large elliptic flow  Large early pressure gradients and gluon densities “chemical” equilibration: Small net baryon density(K+/K-,B/B ratios) mB ~ 25 - 40 MeV Quark coalescence (B/B ratios) Chemical Freezeout T (from global particle ratios) T = 177 MeV, mB = 29 MeV “thermal” equilibration : Thermal freezeout + large transverse flowTFO = 100-110 MeV, bT = 0.5 – 0.6c expansion dynamics: No long-lived mixed phase (from Bose-Einstein correlations) Short chemical-to-thermal freeze-out interval (particle spectra, resonances and particle yields, multi-strange baryons spectra, HBT correlations) John Harris (Yale University) QCD@Work 2003, Bari, Italy

  19. leading particle hadrons hadrons leading particle From theQuark-Gluon QuagmireEmerges Hard Scattering New for heavy ion physics Hard Parton Scattering • sNN = 200 GeV at RHIC (vs 17 GeV at SPS) Jets and mini-jets  30 - 50 % of particle production high pt leading particles (jets?) azimuthal correlations Scattered partons propagate radiate energy (~ few GeV/fm) in colored medium  suppression of high pt particles  alter di-jets and azimuthal correlations John Harris (Yale University) QCD@Work 2003, Bari, Italy

  20. AA cross section NN cross section Nuclear overlap integral: # binary NN collisions / inelastic NN cross section AA (pQCD) Suppression: Parton energy loss R < 1 at large Pt Hadron Spectra: Comparison of AA to NN Nuclear Modification Factor RAA: AA = Nucleus-Nucleus NN = Nucleon-Nucleon John Harris (Yale University) QCD@Work 2003, Bari, Italy

  21. Suppression of Hadron Production Observed at RHIC FNAL fixed target RAA K. Adcox et al. , Phys. Rev. Lett. 88, 022301 (2002) ratio of central AA /scaledpp C. Adler et al. , Phys. Rev. Lett. 89, 202301 (2002) R = 1 QCD RHIC: RAA < 1 for central Au+Au Transverse Momentum (GeV/c) Comparison: pA and Pb+Pb to p+p at Lower s CERN SPS Ions – central collisions R > 1 nuclear effects (Cronin)  Initial state soft multiple scattering (Cronin effect) SPS: If any parton energy loss, it is overwhelmed by initial state soft multiple scattering (Cronin effect) John Harris (Yale University) QCD@Work 2003, Bari, Italy

  22. Inclusive Hadron pt-spectra: s = 200 GeV AuAu STAR PRL 89, 202301 nucl-ex/0305015 Au-Au nucl-ex/0304022 p+phep-ex/0304038 PHENIX nucl-ex/0302015 Submitted to Phys Lett B 200 GeV results from all experiments John Harris (Yale University) QCD@Work 2003, Bari, Italy

  23. Centrality dependence of RAA in Au+Au at s = 200 GeV STAR h+/- nucl-ex/0304022 nucl-ex/0305015 Au-Aunucl-ex/0304022 John Harris (Yale University) QCD@Work 2003, Bari, Italy

  24. Centrality dependence of RAA in Au+Au at s = 200 GeV STAR h+/- nucl-ex/0305015 John Harris (Yale University) QCD@Work 2003, Bari, Italy

  25. STAR Au+Au preliminary Particle Species Dependence of RCP (central/peripheral)in Au+Au at s = 200 GeV • 1.5<pT<3.5 GeV/c: baryons not suppressed  p, L scales ~ Nbinary • p0, K0s suppressed • by pT ~ 6 GeV/c:L, K0s, charged hadrons scale similarly • explanations? • Partonic flow? Quark recombination? Modified fragmentation? Cronin effect? John Harris (Yale University) QCD@Work 2003, Bari, Italy

  26. Jet event in e+e-collision STAR Au+Au (jet?) event Jets at RHIC? STAR p + p  jet event Can we see jets in high energy Au+Au? John Harris (Yale University) PANIC02, Osaka, Japan

  27. Hard Scattering: Two-Particle Azimuthal Correlations Technique: Azimuthal correlation function Trigger particle pT > 4 GeV/c Associate tracks 2 < pT < pT(trigger) STAR di-jets from p + p at 200 GeV John Harris (Yale University) QCD@Work 2003, Bari, Italy

  28. Using p+p Di-jets to Study Central Au+Au Jets -Away-side Jet Disappears Assume: high pT triggered Au+Au event is a superposition: high pT triggered p+p event + elliptic flow of AuAu event Central Au + Au Peripheral Au + Au disappears • v2 from reaction plane analysis • A from fit in non-jet region (0.75 < || < 2.24) Away-side jet John Harris (Yale University) QCD@Work 2003, Bari, Italy

  29. High Pt Particle Suppression  Jet Suppression STAR PRL 90, 082302 STAR Preliminary Hadron suppression disappearance of back-to-back ‘jet’! John Harris (Yale University) QCD@Work 2003, Bari, Italy

  30. Experiment Confronts Theory pQCD-I: Wang, nucl-th/0305010 pQCD-II: Vitev and Gyulassy, PRL 89, 252301 Saturation: KLM, Phys Lett B561, 93 STAR nucl-ex/0305015 pT > 5 GeV/c data described by saturation model (up to 60% central) and pQCD + jet quenching John Harris (Yale University) QCD@Work 2003, Bari, Italy

  31. Disentangling Initial and Final State Effects at RHIC! Effect of “Cronin” and nuclear shadowing + quenching Measure d+Au (for initial state effects) compare to p+p and Au+Au I. Vitev & M. Gyulassy, Phys.Rev.Lett. 89 (2002) pQCD + jet-quenching SPS: Cronin dominant RHIC: Cronin, shadow, quench (dNg/dy)  RAA “flat” John Harris (Yale University) QCD@Work 2003, Bari, Italy

  32. No Suppression Observed in d + Au at RHIC! PHENIXPreliminary h± po PHOBOS Preliminary h± STAR Preliminary h± John Harris (Yale University) QCD@Work 2003, Bari, Italy

  33. No Suppression Observed in d + Au at RHIC! STAR Preliminary h± John Harris (Yale University) QCD@Work 2003, Bari, Italy

  34. Comparing p + p, d + Au and Au + Au Jets STAR preliminary d + Au di-jets ~ p + p di-jets vs disappearance of central Au + Au away-side jet John Harris (Yale University) QCD@Work 2003, Bari, Italy

  35. High Pt Summary x Hadron spectra (vs binary scaling) High Pt hadrons suppressed in central Au + Au enhanced in d + Au Back-to-back Jets Di-jets in p + p, d + Au (all centralities) Away-side jets quenched in central Au + Au emission from surface John Harris (Yale University) QCD@Work 2003, Bari, Italy

  36. Future at RHIC – Hard Probes Charmonium (cc suppression/enhancement)- PHENIX start Open Charm (charm production rates) – PHENIX recent PRL PHENIX - K. Adcox et al., Phys. Rev. Lett. 88, 192303 (2002) Higher Pt triggers, jets  fix parton energy loss (theory…) Quantitative answers to questions on properties Polarized pp measurements up to s = 500 GeV (gluon and sea-quark contribution to proton spin) Direct Photon Radiation? New phenomena……. John Harris (Yale University) QCD@Work 2003, Bari, Italy

  37. Thanks • STAR, PHENIX, BRAHMS, PHOBOS Collaborations • RHIC Operations Group • for contributions and/or discussions: • W. Busza • Drees • M. Gyulassy • D. Hardtke • P. Jacobs • M. Miller • T. Ullrich • F. Videbaek • X.N. Wang • W. Zajc • And all others I forgot to mention K. Adcox et al. , Phys. Rev. Lett. 88, 22301 (2002) John Harris (Yale University) QCD@Work 2003, Bari, Italy

  38. K. Adcox et al. , Phys. Rev. Lett. 88, 22301 (2002) End of Presentation Extra Slides Follow John Harris (Yale University) QCD@Work 2003, Bari, Italy

  39. nonlinear interaction of gluons dE/dx ~ few GeV/fm Baier et al (1998) Linear dep. on gluon density • nonlinear interaction of gluons in thin plasma Gyulassy et al (2001) Energy Loss of Scattered Partons in Dense Matter • How can we determine the parton’s energy loss? • elastic scattering of partons dE/dx ~ 0.1 GeV/fm Bjorken (1983) John Harris (Yale University) QCD@Work 2003, Bari, Italy

  40. Do We Know the Energy Loss in Confined Matter? Wang and Wang, hep-ph/0202105 F. Arleo, hep-ph/0201066 Modification of fragmentation in e-Nucleus scattering: 10 GeV quark: dE/dx ~ 0.5 GeV/fm x1 Drell-Yan production in p-Nucleus: 50 GeV quark: dE/dx <0.2 GeV/fm John Harris (Yale University) QCD@Work 2003, Bari, Italy

  41. Suppression at RHIC: Data Confronts Theory Properties of the Medium • Parton Energy Loss : dE/dx ≈ 0.25 GeV/fm (expanding) dE/dx|eff ≈ 7 GeV/fm (static source) ~ 15 times that in cold Au nuclei • Opacities: <n> = L/≈ 3 – 4 • Gluon densities: dNg/dy ~ 900 John Harris QCD@Work 2003, Bari, Italy

  42. “High” Pt Summary - Exp vs Theory Wang and Wang, hep-ph/0202105 Preliminary sNN = 200 GeV Ivan Vitev, QM2002 Observe: strong suppression of high Pt hadrons Requires: dE/dx = 7.3 GeV/fm ~ 10-15 times cold matter gluon densities dngluon/dy ~ 500 – 1000 John Harris (Yale University) QCD@Work 2003, Bari, Italy

  43. probe rest frame r/ ggg Suppression: an initial state effect? • Gluon Saturation • (color glass condensate) Wavefunction of low x gluons overlap; the self-coupling gluons fuse, saturating the density of gluons in the initial state.(gets Nch right!) • Multiple elastic scatterings (Cronin effect) Wang, Kopeliovich, Levai, Accardi • Nuclear shadowing Gribov, Levin, Ryshkin, Mueller, Qiu, Kharzeev, McLerran, Venugopalan, Balitsky, Kovchegov, Kovner, Iancu … RdAu~ 0.5 D.Kharzeev et al., hep-ph/0210033 Broaden pT :

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