1. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 Evidence for a Quark-Gluon Plasma at RHIC Part 2

2. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 Creating and Probing the Quark-Gluon Quagmire at RHIC John Harris Yale University NATO ASI, Kemer, Turkey 2003

3. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 PHOBOS Au + Au On the “First Day” (at RHIC) Large energy densities  dn/d  dE T /d   GeV/fm 3  critical  x nuclear density Large collective flow ed. - “completely unexpected!”  Large early pressure gradients, energy & gluon densities  Hydrodynamic & requires quark-gluon equation of state! Quark flow & coalescence  constituent quark degrees of freedom! PHENIX Initial Observations: Large produced particle multiplicities ed. - “less than expected!  gluon-saturation?”  dn ch /d  |  =0 = 670, N total ~ 7500  15,000 q +  q in final state, > 92% are produced quarks CGC?

4. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 STAR, PRL90 032301 (2003) b ≈ 4 fm b ≈ 6.5 fm b ≈ 10 fm peripheral collisions Top view Beams-eye view On the First Day at RHIC - Azimuthal Distributions 1

5. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 Early Pressure in System  Elliptic Flow! x z y Sufficient interactions early (< 1 fm/c) in system  to respond to early pressure!  before self-quench (insufficient interactions)! System is able to convert original spatial ellipticity  momentum anisotropy! Sensitive to early dynamics of system p p Azimuthal anisotropy (momentum space) 1

6. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 Elliptic Flow Saturates Hydrodynamic Limit Azimuthal asymmetry of charged particles: dn/d  ~ 1 + 2 v 2 (p T ) cos (2  ) +... x z y curves = hydrodynamic flow zero viscosity, Tc = 165 MeV 1 Mass dependence of v 2 Requires - Early thermalization (0.6 fm/c) Ideal hydrodynamics (zero viscosity)  “nearly perfect fluid”  ~ 25 GeV/fm 3 ( >>  critical ) Quark-Gluon Equ. of State

7. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 If baryons and mesons form from independently flowing quarks then quarks are deconfined for a brief moment (~ 10 -23 s), then hadronization!

8. Transport in gases of strongly-coupled atoms RHIC fluid behaves like this – a strongly coupled fluid. Universality of Classical Strongly-Coupled Systems Universality of classical strongly-coupled systems?  Atoms, sQGP, AdS/CFT……

9. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 Ultra-low (Shear)Viscosity Fluids 4    s Quantum lower viscosity bound:  s > 1/4  ( Kovtun, Son, Starinets ) From strongly coupled N = 4 SUSY YM theory. 2-d Rel Hydro describes STAR v 2 data with  /s  0.1 near lower bound!  s (limit) = 1/4  s (water) >10 QGP

10. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 Ultra-low Viscosity Fluids Scientific American, November 2005 “A test comes from RHIC ….. A preliminary analysis of these experiments indicates the collisions are creating a fluid with very low viscosity.” “Black holes have an extremely small shear viscosity – smaller than any known fluid… Strongly interacting quarks and gluons at high T should also have a very low viscosity.”

11. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 “The RHIC fluid may be the least viscous non-superfluid ever seen” The American Institute of Physics announced the RHIC quark-gluon liquid as the top physics story of 2005! see http://www.aip.org/pnu/2005/

12. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 It Flows - Is It Really Thermalized? “Chemical” equilibration (particle yields & ratios): Particles yields represent equilibrium abundances  universal hadronization temperature Small net baryon density  K + /K -,  B/B ratios)  B ~ 25 - 40 MeV Chemical Freezeout Conditions  T = 177 MeV,  B = 29 MeV  T ~ T critical (QCD)

13. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 QCD Phase Diagram At RHIC: T = 177 MeV T ~ T critical (QCD)

14. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 Particles are thermally distributed and flow collectively, at universal hadronization temperature T = 177 MeV!

15. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 Probing Hot QCD Matter with Hard-Scattered Probes hadrons leading particle hadrons leading particle

16. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 High Momentum Hadrons Suppressed - Photons Not Photons Hadrons factor 4 – 5 suppression dev Deviations from binary scaling of hard collisions:

17. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 Final State Suppression / Initial State Enhancement! The hadron spectra at RHIC from p+p, Au+Au and d+Au collisions establish existence of early parton energy loss, a new final-state effect, from strongly interacting, dense QCD matter in central Au-Au collisions Au + Au Experimentd + Au Control Experiment Final Data

18. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 Energy Loss of Hard Scattered Parton dev Energy loss requires large p T = 4.5 – 10 GeV/c (Dainese, Loizides, Paic, hep-ph/0406201) Much larger energy loss than expected from perturbation theory Pion gas QGP Cold nuclear matter RHIC data sQGP R. Baier

19. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 Heavy Charm and Beauty Quarks Late Breaking News Heavy quarks thought too massive to be attenuated by medium! Single non-photonic electrons (from D and B mesons) → suppressed! Heavy quarks flow like light quarks! Au + Au  non-photonic electrons

20. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 Hard Scattering (Jets) as a Probe of Dense Matter II Jet event in e  e   collision STAR p + p  jet event Can we see jets in high energy Au+Au? STAR Au+Au (jet?) event

21. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 Hard Scattering: Two-Particle Azimuthal Correlations Technique: Azimuthal correlation function Trigger particle p T > 4 GeV/c Associate tracks 2 < p T < p T (trigger) STAR di-jets from p + p at 200 GeV

22. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 Hard Scattering: Two-Particle Azimuthal Correlations Technique: Azimuthal correlation function Trigger particle p T > 4 GeV/c Associate tracks 2 < p T < p T (trigger) STAR  < 0.5  > 0.5 short range  correlation: jets + elliptic flow long range  correlation: elliptic flow 130 GeV Au + Au, central trigger

23. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 Relative Charge Dependence Compare ++ and - - correlations to +- STAR Preliminary @ 200 GeV/c 0-10% most central Au+Au p+p minimum bias 4<p T (trig)<6 GeV/c 2<p T (assoc.)<pT(trig) |  | 0.5 (scaled) 0<|  |<1.4 Au+Au p+p System(+-)/(++ & --) p+p2.7+-0.6 0-10% Au+Au2.4+-0.6 Jetset2.6+-0.7 Strong dynamical charge correlations in jet fragmentation  “charge ordering” Ref: PLB 407 (1997) 174. p T > 4 GeV/c particle production mechanism same in central Au+Au & pp |  | 0.5 (scaled) 0<|  |<1.4 Au+Au p+p

24. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 Using p+p to Study Au+Au Jet Correlations Assume: high p T triggered Au+Au event is a superposition: high p T triggered p+p event + elliptic flow of AuAu event –v 2 from reaction plane analysis –A from fit in non-jet region (0.75 < |  | < 2.24) Peripheral Au + Au Away-side jet Central Au + Au disappears STAR 200 GeV/c peripheral & central Au+Au p+p minimum bias 4<p T (trig)<6 GeV/c 2<p T (assoc.)<pT(trig)

25. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 Hammering the Nail in the Coffin Pedestal&flow subtracted no jet quenching! d + Au “di-jet” correlations similar to p + p Au + Au away-side correlation quenched! Quenching of Away-side “jet” is final state effect

26. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 Hard Scattering Conclusions 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  strongly interacting medium x

27. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 Where Does the Energy Go? dev Jet correlations in proton-proton reactions. Strong back-to- back peaks. Jet correlations in central Gold-Gold. Away side jet disappears for particles p T > 2 GeV Jet correlations in central Gold-Gold. Away side jet reappears in particles p T > 200 MeV Azimuthal Angular Correlations Lost energy of away-side jet is redistributed to rather large angles! Color wakes? J. Ruppert & B. Müller Mach cone from sonic boom? H. Stoecker J. Casalderrey-Solana & E. Shuryak Cherenkov-like gluon radiation? I. Dremin A. Majumder, X.-N. Wang

28. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 Charmonium Suppression - Deconfinement Late News Color screening of cc pair results in J/  (cc) suppression! J/  suppressed but less than expected? (more to do!) Suppression Factor

29. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 Experimental Evidence for Initial State Gluon Saturation Suppression of forward hadrons consistent with saturation of low-x gluons. Au d d d x ~ 10 -3 x ~ 10 -2 x ~ 10 -1 Centrality dependence & x dependence test CGC Suppression Factor x ~ 10 -4 x ~ 10 -3

30. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 Summary Quark coalescence /flow  constituent quark degrees of freedom Extreme initial densities –  5 GeV/fm 3  ~ 30 - 100 x nuclear density > 15,000 q +  q in final state Equilibrium particle abundances – Universal hadronization T ~ T crit Rapid u, d, s equilibration near T crit Jet energy loss – large gluon densities  strongly coupled QGP Ideal hydrodynamic flow → “perfect fluid” - Early thermalization & Quark-Gluon EOS Strongly-coupled system of quarks and gluons (sQGP) formed at RHIC Initial state gluon saturation (color glass condensate?) - forward rapidities  low-x d+Au is suppressed x ~ 10 -4 x ~ 10 -3 p+p Trigger jet Away- side jet Au+Au

31. John Harris (Yale) D. Allan Bromley Symposium, 8 - 9 December 2005 Signatures & Properties of the QGP at RHIC Large  >  c (T > T c ) system – QCD vacuum “melts” – NOT hadrons Thermalized system of quarks and gluons – NOT just q & g scattering Large elliptic & radial flow  fluid flow (“perfect”!) Heavy quark (charm) flow Particle ratios fit by thermal model  T = 177 MeV ~ T c (lattice QCD) System governed by quark & gluon Equation of State – NOT hadronic Flow depends upon particle (constituent quark & gluon) masses  QGP EoS,, quark coalescence Deconfined system of quarks and gluons – NOT hadrons Flow already at quark level, charmonium suppression (tbd) Weakly-interacting QGP (predicted by Lattice QCD) – NOT!!! Strongly interacting quarks and gluons  ….degrees of freedom (tbd) Strongly-interacting QGP (NOT predicted by Lattice QCD) Suppression of high p T hadrons, away-side jet quenched Large opacity (energy loss)  extreme gluon/energy densities  strongly-interacting QGP (sQGP)

32. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 Shuryak, QM04 (flavor) Still to do! Deconfined QGP?  cc,  bb suppression & melting sequence Chiral symmetry restoration? Thermalized heavy flavors? Open charm, beauty, multiply-strange baryon production & flow Establish properties of the sQGP medium Constituents? Transport properties (speed of sound, diffusion…) Flavor dependence of suppression & propagation Light vector mesons (mass and width modifications in medium) Direct Photon Radiation? New phenomena……. LHC & 40 x luminosity of RHIC & e-ion collider! Developments in theory (lattice, hydro, parton E-loss) “the adventure continues!”

33. John Harris (Yale) D. Allan Bromley Symposium, 8 - 9 December 2005 Special Thanks for Contributions to This Presentation!! Mike Lisa Berndt Mueller Jamie Nagle Paul Sorenson

34. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 Use Geometry to Vary Parameters of Collision x z y

35. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 Path Length Dependence of Di-jet Topologies y x p T trigger =4-6 GeV/c, 2<p T associated <p T trigger, |  |<1 in-plane Out-of-plane Back-to-back suppression out-of-plane stronger than in-plane Effect of path length on suppression is experimentally accessible

36. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 Centrality Dependence of Suppression at RHIC Au+Au 130 GeV Phys. Rev. Lett. 89, 202301 (2002) STAR

37. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 Identified Particles - High p T Suppression Two groups (2 < p  < 6GeV/c): -   baryons - K 0 s, K , K*   mesons R cp Not a mass dependent effect Rather baryons / mesons Merge at p  ~ 6 GeV? Fragmentation?  and  behavior different from K Suppression of K starts at lower p  (latest data -  same as K)  K Mass or meson/baryon effect?

38. 6/12/2005 HI Future J. Schukraft What is left to do at LHC ?  Search for the QGP may be essentially over  Discovery of QGP is well under way (with fantastic results & surprises at RHIC)  Measuring QGP parameters has hardly begun pre-RHIC tasks:precision measurements  quantitative and systematic study of this state of matter (‘ LEP after W/Z discovery at SppS’)  different state (by large factors) in energy density, lifetime, volume  new signals (‘hard probes’) : heavy quark states (b,c), jets post – RHIC result tasks:continue discovery !  confirm interpretations by testing predictions/extrapolation to LHC  is initial state dominated by yet another new state of matter (dense quantum state) ?  Color Glass Condensate ? (QCD in classical Field Theory limit ) surprises may still lie aheadmore to search for ?  transition from strongly coupled QGP -> ideal QGP ? Assumption: ‘QGP’ has been established at RHIC prior to LHC

39. John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04 Do We Know the Energy Loss in Confined Matter? Wang and Wang, hep-ph/0202105 Modification of fragmentation in e-Nucleus scattering: 10 GeV quark: dE/dx ~ 0.5 GeV/fm F. Arleo, hep-ph/0201066 x1 Drell-Yan production in  -Nucleus: 50 GeV quark: dE/dx <0.2 GeV/fm

40. John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04 Medium properties according to “jet quenching” models: Initial gluon densities: dN g /dy ~ 1100 [Vitev & Gyulassy] Opacities: L/  ≈ 3 – 4 [Levai et al.] Transport coefficients: ~ 3.5 GeV/fm 2 [BDMPS, F.Arleo ] Plasma temperatures: T ~ 0.4 GeV [G. Moore] Medium-induced radiative energy losses: [X.N.Wang] dE/dx ≈ 0.25 GeV/fm (expanding) dE/dx| eff ≈ 14 GeV/fm (static source) Such large opacities imply: (i) large rescattering: thermalization (ii) energy densities ε crit QCD >> 1 GeV/fm 3 Theory vs. data  very dense medium

41. John Harris (Yale) Gordon Research Conference on Nuclear Physics, 2005 1) completely unexpected STAR V2 flow results on day 1 1b) to the combined STAR and PHENIX flow for identified particles that begs for the right dynamical approach and sophistication to describe them in order to extract the nuclear matter equation of state (softness) and properties (such as transport properties of the matter: viscosity - primarily shear, heat conductivity, speed of sound). Added later – quark coalescence as seen in v2 and thermalization as seen in particle ratios and thermal model fits. 2) the remarkable high Pt hadron suppression seen in AuAu but not in dAu by all RHIC experiments. Evidence for high density matter, supporting the initial PHENIX (from dET/d(eta)) and STAR (from dn/d(eta)) determination of the large energy densities created at RHIC. This will continue to be investigated at RHIC and RHIC II thru measurements at larger Pt and the use of particle identification to understand the energy loss differences for various propagating partons (quarks, gluons, light and heavier quarks). 3) the observation of away-side jet quenching (or even absence of the away-side jet) in central collisions gave further support to an evolving theoretical descriptions in terms of a strongly-coupled QGP, not the perturbative one that we all expected from predictions. This is an exciting twist that will open up the field even more than we could imagine, both from the perspective of our trying to understand what is this unexpected medium (not one previously predicted) and what are its constituents, to the perspective of our field branching out to other fields of physics where similar theoretical techniques are being used to attempt to understand very different sets of results (e.g. strongly-interacting atomic gases and strongly-interacting QGP). In the end, again utilization of a variety of probes (propagating quarks, gluons, light and heavy quarks) in RHIC collisions will help identify the way the medium interacts with these probes of differing properties.

42. John Harris (Yale) Gordon Research Conference on Nuclear Physics, 2005 4). new, preliminary results of the flow of charm defy earlier predictions. More detailed charm particle measurements to larger Pt are needed. Studies of the propagation of fast heavy quarks are required. [Heavy quarks at large Pt clearly leads to detector upgrades, RHIC II and new detector and experiment ideas.] 5) and we'll start to address deconfinement soon (with J/psi, albeit from chi_c feed-down) and complete the program in the future (with the psi' and Upsilon states at RHIC II). 6) and we'll need to keep trying to address chiral symmetry restoration thru low mass dileptons and with possibly a better understanding of hadronization/fragmentation in vacuum and in medium (in the future) or other new ideas. To do for talk – Add Rcp for PID?

43. Wakes in the QGP Mach cone requires collective mode with  (k) < k : J. Ruppert and B. Müller, Phys. Lett. B 618 (2005) 123 Colorless sound ? Colored sound = longitudinal gluons ? Transverse gluons pQCD (HTL) dispersion relation

44. Collective modes in medium Cherenkov-like gluon radiation into a space-like transverse gluon branch: I. Dremin A. Majumder, X.-N. Wang, hep-ph/0507062 Mach cone structures from a space- like longitudinal plasmon branch: J. Ruppert & B. Müller, Phys. Lett. B 618 (2005) 123 Mach cone from sonic boom: H. Stoecker J. Casalderrey-Solana & E. Shuryak “Colored” sound Longitudinal (sound) modes Transverse modes Normal sound

45. John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006 Crucial Control Measurement – d + Au Collisions Crucial control measurement - d + Au not suppressed! d + Au Au + Au