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Out of the Quark-Gluon Quagmire Emerge Hard Signals

Out of the Quark-Gluon Quagmire Emerge Hard Signals. John Harris Yale University. Introduction Relativistic Heavy Ion Physics Relativistic Heavy Ion Collider (RHIC) + RHIC Experiments General Characteristics of RHIC Collisions Soft Physics - “Brief Overview”

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Out of the Quark-Gluon Quagmire Emerge Hard Signals

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  1. Out of the Quark-Gluon Quagmire Emerge Hard Signals John Harris Yale University • Introduction • Relativistic Heavy Ion Physics • Relativistic Heavy Ion Collider (RHIC) • + RHIC Experiments • General Characteristics of RHIC Collisions • Soft Physics - “Brief Overview” • High PT Physics – “Hard Results” • Summary and Outlook John Harris (Yale University) ICHEP 2002, Amsterdam

  2. “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 bydistributing high energy over a relatively large volume.” T.D. Lee Rev. Mod. Phys. 47 (1975) 267. John Harris (Yale University) ICHEP 2002, Amsterdam

  3. 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) ICHEP 2002, Amsterdam

  4. 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 • “Applications”? • Quark-hadron phase transition in early Universe • Cores of dense stars • High density QCD John Harris (Yale University) ICHEP 2002, Amsterdam

  5. Collisions at RHIC John Harris (Yale University) ICHEP 2002, Amsterdam

  6. STAR PHENIX RelativisticHeavyIonCollider RHIC John Harris (Yale University) ICHEP 2002, Amsterdam

  7. PHENIX Axial Field High Resolution & Rates 2 Central Arms, 2 Forward Arms TEC, RICH, EM Cal, Si, TOF, -ID STAR Solenoidal field Large- Tracking TPC’s, Si-Vertex Tracking RICH, EM Cal, TOF • Leptons, Photons, & Hadrons • Simultaneous Detection of • Various Transition Phenomena • Hadronic Observables • Large Acceptance, Jets • Event-by-Event Analyses The Two “Large” Experiments at RHIC John Harris (Yale University) ICHEP 2002, Amsterdam

  8. BRAHMS PHOBOS STAR PHENIX RelativisticHeavyIonCollider RHIC John Harris (Yale University) ICHEP 2002, Amsterdam

  9. BRAHMS 2 Spectrometers PHOBOS “Table-top” Spectrometer 95° 30° 2.3° 30° 15° • Inclusive Particle Production • Large Rapidity Range • Charged Hadrons • Particle Correlations The Two “Smaller” Experiments at RHIC John Harris (Yale University) ICHEP 2002, Amsterdam

  10. BRAHMS PHOBOS RHIC PHENIX STAR Ions: A = 1 ~ 200, pp, pA, AA, AB RelativisticHeavyIonCollider Two Concentric Superconducting Rings Design PerformanceAu + Aup + p Max snn 200 GeV 500 GeV L [cm-2 s -1 ] 2 x 10261.4 x 1031 Interaction rates 1.4 x 103 s -1 3 x 105 s -1 John Harris (Yale University) ICHEP 2002, Amsterdam

  11.  Ldt RHIC 2000 Run (June – Sept 2000) Au+Au snn = 130 GeV RHIC 2001 Au+Au Run (Aug – Nov 2001) snn = 200 GeV Days into RHIC Run RHIC Running Days into RHIC Run John Harris (Yale University) ICHEP 2002, Amsterdam

  12. z y x Collisions at RHIC Centrality impact parameter (b) selection on collision geometry participants: nucleons in nuclear overlap “peripheral” = collision (b ~ bmax) “central” = head-on collision (b ~ 0) John Harris (Yale University) ICHEP 2002, Amsterdam

  13. Au on Au Event at CM Energy ~ 130 A-GeV Peripheral Event color code energyloss John Harris (Yale University) ICHEP 2002, Amsterdam

  14. Au on Au Event at CM Energy ~ 130 A-GeV Mid-central Event color code energyloss John Harris (Yale University) ICHEP 2002, Amsterdam

  15. Au on Au Event at CM Energy ~ 130 A-GeV Central Event color code energyloss John Harris (Yale University) ICHEP 2002, Amsterdam

  16. s = 200 GeV 200 GeV 130 GeV q central UA5pp inelastic dN/dh/Npart/2 q similar shapes at ycm 3 19.6 GeV 900 GeV 2 546 GeV 0 200 GeV yT 1 53 GeV 0 h = h - ybeam -2 0 -4 -6 yT General Characteristics of RHIC Collisions Au + Au, Pb + Pb scaling in forward region P. Steinberg John Harris (Yale University) ICHEP 2002, Amsterdam

  17. p+p  p+X A+A e+e- pp/pp Universality pp e+e- Au+Au (Mueller 1983) P. Steinberg General Characteristics of RHIC Collisions Central A+A John Harris (Yale University) ICHEP 2002, Amsterdam

  18. Soft Physics – Brief Overview from the > (28 + 11) refereed journal publications from RHIC experiments: Large Particle Multiplicities  dnch/dh|y=0= 670, Ntotal ~ 6000 Large energy densities(dET/dh) e  5 GeV/fm3/ t (t ~ 0.1 – 1) Low net baryon density(B/B ratios)  mB ~ 40 MeV Chemical Freezeout T(particle ratios)  T ~ 170 MeV Hadronization (dnch/dh|y=0 , particle ratios) AA ~ e+e- saturation, statistical hadronization, fragmentation (universality)? Expansion and Thermal Freezeout quark coalescence(B/B ratios) no long-lived mixed phase (Bose-Einstein correlations) rather - freezeout at critical point or rapid hadronization short chemical-to-thermalfreeze-out interval (particle spectra, resonances and particle yields, multi-strange baryons spectra, HBT correlations) Space-time evolution of interaction still being determined John Harris (Yale University) ICHEP 2002, Amsterdam

  19. early universe 250 quark-gluonplasma 200 RHIC Temperature Tchemical freezeout (MeV) SPS lattice QCD 150 deconfinement chiral restauration thermal freeze-out AGS 100 hadron gas SIS 50 neutron stars nuclei 0 0 200 400 600 800 1000 1200 Baryonic Potential B (MeV) Nuclear Phase Diagram P. Braun-Munzinger nucl-ex/0007021 John Harris (Yale University) ICHEP 2002, Amsterdam

  20. p L p K f e jet m g Freeze-out Hadronization QGP Pre-equilibrium Au Au Space-time Evolution of Collisions time g e  Expansion  space John Harris (Yale University) ICHEP 2002, Amsterdam

  21. leading particle hadrons hadrons leading particle Out of theQuark-Gluon QuagmireHard Scattering at RHIC John Harris (Yale University) ICHEP 2002, Amsterdam

  22. leading particle hadrons • Scattered partons propagate through matter radiate energy (~ few GeV/fm) in colored medium • suppression of high pt particles called “parton energy loss” or “jet quenching” • alter di-jets and azimuthal correlations leading particle vacuum hadrons medium Hard Scattering as a Probe at RHIC • 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 John Harris (Yale University) ICHEP 2002, Amsterdam

  23. Nuclear Modification Factor RAA R > 1 nuclear effects (Cronin) RAA TAA: nuclear overlap integral (from Glauber model) R = 1 QCD  If any parton energy loss, it is overwhelmed by initial state soft multiple scattering (Cronin effect) Transverse Momentum (GeV/c) Comparison of Pb+Pb to p+p at s = 17.2 GeV John Harris (Yale University) ICHEP 2002, Amsterdam

  24. s = 130 GeV Au + Au STAR preliminary charged particles power law: pp = d2N/dpt2 = A (p0+pt)-n Inclusive Hadron pt-distributions John Harris (Yale University) ICHEP 2002, Amsterdam

  25. High-pT Spectra in 130 GeV Au+Au Collisions spectra from PHENIX + STAR agree over 6 orders of magnitude John Harris (Yale University) ICHEP 2002, Amsterdam

  26. J.C. Dunlop et al. , Nucl. Phys. A 698, 515c (2002) Suppression of Hadron Production K. Adcox et al. , Phys. Rev. Lett. 88, 22301 (2002) ratio of central AA /scaledpp • RAA < 1 for central Au+Aureactions at RHIC (130 AGeV) • observed in (PHENIX and STAR) John Harris (Yale University) ICHEP 2002, Amsterdam

  27. STAR Centrality Dependence of Suppression Au+Au 130 GeV submitted to PRL, nucl-ex/0206011 John Harris (Yale University) ICHEP 2002, Amsterdam

  28. Inclusive Hadron pt-spectra: s = 200 GeV AuAu Identified pions Preliminary STAR 200 GeV results from all experiments John Harris (Yale University) ICHEP 2002, Amsterdam

  29. Preliminary sNN = 200 GeV Central/Peripheral Comparisons suppression increases up to pT = 6 GeV/c 0.5 suppression saturates beyond pT ~6 GeV/c 0.5  130 GeV • 200 GeV John Harris (Yale University) ICHEP 2002, Amsterdam

  30. Comparison with N+N Reference Data Suppressionincreases with centrality more pronounced at higher pT John Harris (Yale University) ICHEP 2002, Amsterdam

  31. z y x Azimuthal Correlations in AA Collisions Short-range correlations jets, resonances Long-range correlations momentum conservation, az. anisotropy of event (soft) John Harris (Yale University) ICHEP 2002, Amsterdam

  32. Y X f XZ-plane - the reaction plane 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 (Yale University) ICHEP 2002, Amsterdam

  33. t = 3.2 fm/c y (fm) t = 8 fm/c x (fm) Hydrodynamic Calculation of Elliptic Flow P. Kolb, J. Sollfrank, and U. Heinz Equal energy density lines John Harris (Yale University) ICHEP 2002, Amsterdam

  34. Charged Particle Elliptic Flow (v2) STAR preliminary Hydrodynamics + hard scattering (M. Gyulassy, I. Vitev & X.N. Wang, nucl-th/00012092, PRL) STAR Hydro + hard scattering model and data: hydrodynamic behavior up to ~1.5 GeV/c v2 saturates at high pt reflects gluon density data  compatible with scenario of large parton energy loss in medium Evidence that initial spatial asymmetry is efficiently translated into momentum space anisotropy (as in hydrodynamics) Increasing pressure gradients in the system Azimuthal anisotropy (v2) - increases with Pt - saturates at higher Pt STAR PRL87 (2001)182301 John Harris (Yale University) ICHEP 2002, Amsterdam

  35. Jet event in e+e-collision STAR Au+Au (jet?) event Hard Scattering (Jets) as a Probe at RHIC Can we see jets in high energy Au+Au? John Harris (Yale University) ICHEP 2002, Amsterdam

  36. Hard Scattering via Angular Correlations Charged tracks (1 - 2 GeV/c) associated with a high energy leading photon (>2.5 GeV/c) Remove soft background by subtraction of mixed event distribution. Fit remainder: - particle correlation in f - shape taken from Pythia - add v2 component to account for flow effects PHENIX Preliminary near-side far-side PHENIX John Harris (Yale University) ICHEP 2002, Amsterdam

  37. Two-Particle Azimuthal Correlations Technique: Azimuthal correlation function Trigger particle pT > 4 GeV/c Associate tracks 2 < pT < pT(trigger) Dh < 0.5 Dh > 0.5 STAR • short range  correlation: • jets + elliptic flow • long range  correlation: • elliptic flow John Harris (Yale University) ICHEP 2002, Amsterdam

  38. Relative Charge Dependence Strong dynamical charge correlations in jet fragmentation  “charge ordering” ||<0.5 - ||>0.5 (scaled) Au+Au ||<0.5 - ||>0.5 (scaled) 0<||<1.4 Au+Au p+p 0<||<1.4 Ref: PLB 407 (1997) 174. p+p pT > 4 GeV/c particle production mechanism same in central Au+Au & pp STAR Preliminary @ 200 GeV/c 0-10% most central Au+Au p+p minimum bias 4<pT(trig)<6 GeV/c 2<pT(assoc.)<pT(trig) Compare ++ and - - correlations to +- John Harris (Yale University) ICHEP 2002, Amsterdam

  39. Using p+p to Study Au+Au Jet Correlations Assume: high pT triggered Au+Au event is a superposition: high pT triggered p+p event + elliptic flow of AuAu event Central Au + Au 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) ICHEP 2002, Amsterdam

  40. Summary – “High” Pt Suppression at High Pt Central Peripheral • See jet characteristics • Away-side jet quenched • in central AuAu K. Adcox et al. , Phys. Rev. Lett. 88, 22301 (2002) Qualitative changes ~ 2 GeV/c John Harris (Yale University) ICHEP 2002, Amsterdam

  41. Summary – “High” Pt After first 2 RHIC Runs – Picture emerging: rapid formation of dense medium high Pt hadrons suppressed jets quenched emission from surface? Need theory input on: space-time evolution (dynamic models) energy loss estimate: dE/dx ~ 10-15 times cold matter quarks on lattice medium effects fragmentation function (baryons and mesons at high z) K. Adcox et al. , Phys. Rev. Lett. 88, 22301 (2002) John Harris (Yale University) ICHEP 2002, Amsterdam

  42. Outlook – “High” Pt Still ahead: Charmonium (cc suppression/enhancement) Higher Pt triggers, EMC, jets? pA, dA for nuclear effects (hard scattering, gluon structure function) Open Charm (charm production rates) Polarized pp measurements up to s = 500 GeV (gluon and sea-quark contribution to proton spin) Understand gluon saturation (link between RHIC & HERA!) Direct Photon Radiation? Answers to questions on “new phenomena”……. John Harris (Yale University) ICHEP 2002, Amsterdam

  43. Thanks STAR, PHENIX, BRAHMS, PHOBOS Collaborations RHIC Operations Group for contributions and/or discussions: A. Drees D. Hardtke J. Klay M. Miller J. Nagle T. Peitzmann R. Snellings P. Steinberg T. Ullrich W. Zajc And all others I forgot to mention K. Adcox et al. , Phys. Rev. Lett. 88, 22301 (2002) John Harris (Yale University) ICHEP 2002, Amsterdam

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