John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 Heavy Ions - Phenomenology and Status LHC Introduction to Rel. Heavy Ion Physics The Relativistic Heavy Ion Collider (RHIC) Creating Hot Bulk QCD Matter Using Hard Scattering to Probe the Matter Conclusions & Expectations

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 Early Universe National Geographic (1994) & Michael Turner quark-hadron phase transition 2 x Kelvin

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 Lattice QCD at Finite Temperature F. Karsch, et al. Nucl. Phys. B605 (2001) 579 m u,d = m s m u = m d m s  m u,d Action density in 3 quark system in full QCD H. Ichie et al., hep-lat/ G. Schierholz et al., Confinement 2003 Heavy quarks suppressed exp(-m c,b,t /T) T C ~ 175  8 MeV   C ~ GeV/fm 3

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 Hot Bulk QCD Matter (QGP) Standard Model  Lattice Gauge Calculations predict Deconfinement phase transition at high T in QCD Cosmology  Quark-hadron phase transition in early Universe Astrophysics  Cores of dense stars Establish bulk properties of QCD at high T and density Can we make it in the lab?

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 Relativistic Heavy Ion Collider STAR PHENIX PHOBOS BRAHMS RHIC Design PerformanceAu + Aup + p Max  s nn 200 GeV500 GeV L [cm -2 s -1 ]2 x x Interaction rates1.4 x 10 3 s -1 3 x 10 5 s -1 Two Concentric Superconducting Rings Ions: A = 1 ~ 200, pp, pA, AA, AB

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 Relativistic Heavy Ion Collider and Experiments STAR

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 Space-time Evolution of RHIC Collisions e  space time jetjet Hard Scattering + Thermalization (< 1 fm/c) Au  Expansion  Hadronization p K   Freeze-out (~ 10 fm/c)   QGP (~ few fm/c)  e

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 What Can We Learn from Hadrons at RHIC? Can we learn about Hot Nuclear Matter? –Equilibration? Thermodynamic properties? –Equation of State? –How to determine its properties? Hadron Spectrum Soft Physics  reflect bulk properties (p T < 2 GeV/c) (99% of hadrons) Hard Scattering & Heavy Quarks  probe the medium

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 What Have We Learned at RHIC So Far? Large energy densities  dn/d  dE T /d   GeV/fm 3  x nuclear density Collective phenomena: Large elliptic flow  Extreme early pressure gradients & energy densities  Hydrodynamic & requires quark-gluon equation of state! Global observations: Large produced particle multiplicities  dn ch /d  |  =0 = 670, N total ~ 7500  15,000 q +  q in final state, > 92% are produced quarks Quark coalescence / recombination & flow  constituent quark degrees of freedom

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 Elliptic Flow  Early Pressure in System x z y Initial Ellipticity (coord. space) Reaction Plane (xz) Sufficient interactions early (~ 1 fm/c) in system  to respond to early pressure?  before self-quench (insufficient interactions)? System able to convert original spatial ellipticity into momentum anisotropy? Sensitive to early dynamics of initial system p p Azimuthal anisotropy (momentum space) ?

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 Large Elliptic Flow Observed Azimuthal asymmetry of charged particles: dn/d  ~ v 2 (p T ) cos (2  ) +... x z y Particle mass dependence of v 2 requires Early thermalization Ideal hydrodynamics Quark-gluon Equation of State

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 Quark Recombination and Elliptic Flow Complicated v 2 (p T ) flow pattern is observed for identified hadrons d 2 n/dp T d  ~ v 2 (p T ) cos (2  ) If the flow is established at the quark level, it is predicted to be simple when p T → p T / n, v 2 → v 2 / n, n = (2, 3 quarks) for (meson, baryon) quarks flow collectively

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 More Data on v 2 and Quark Recombination e.g. take strange particle v2 v2 of all hadrons obey quark recombination systematics! Au+Au  s NN =200 GeV STAR Preliminary MinBias 0-80%

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 What Have We Learned at RHIC So Far? Large energy densities  dn/d  dE T /d   GeV/fm 3  x nuclear density Collective phenomena: Large elliptic flow  Extreme early pressure gradients & gluon densities  quark-gluon equation of state! Global observations: Large produced particle multiplicities  dn ch /d  |  =0 = 670, N total ~ 7500  15,000 quarks in final state, > 92% are produced quarks “Chemical” equilibration (particle yields & ratios): Particles yields represent equilibrium abundances  universal hadronization temperature Quark coalescence / recombination & flow  constituent quark degrees of freedom

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 Chemically and thermally equilibrated fireball at one temperature T and one ( baryon) chemical potential  : –One ratio (e.g.,  p / p ) determines  / T : –Second ratio (e.g., K /  ) provides T   Then all hadronic yields and ratios determined: Particle Ratios  Chemical Equilibrium  Temperature Ratios  equilibrium values

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 Soft Sector (Bulk Dynamics) -What We Have Learned at RHIC! Large energy densities  dn/d  dE T /d   GeV/fm 3  x nuclear density Collective phenomena: Large elliptic flow  Extreme early pressure gradients & gluon densities  quark-gluon equation of state! Global observations: Large produced particle multiplicities  dn ch /d  |  =0 = 670, N total ~ 7500  15,000 quarks in final state, > 92% are produced quarks “Chemical” equilibration (particle yields & ratios): Particles yields represent equilibrium abundances  universal hadronization temperature Quark coalescence / recombination & flow  constituent quark degrees of freedom Small net baryon density  K + /K -,  B/B ratios)  B ~ MeV Chemical Freezeout Conditions  T = 177 MeV,  B = 29 MeV  T ~ T critical (QCD) “Thermal” equilibration (particle spectra) : Thermal freezeout + large transverse flow  T FO = MeV,  T  = 0.5 – 0.6c

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 QCD Phase Diagram At RHIC: T = 177 MeV T ~ T critical (QCD)

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 Hard Scattering to Probe the Hot Bulk QCD Medium hadrons leading particle hadrons leading particle

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 Inclusive Hadron p t -spectra:  s = 200 GeV AuAu power law:  pp = d 2 N/dp t 2 = A (p 0 +p t ) -n Preliminary STAR

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 Hadron Spectra: Comparison of AA to NN Nuclear Modification Factor R AA : AA = Nucleus-Nucleus NN = Nucleon-Nucleon Nuclear overlap integral: # binary NN collisions / inelastic NN cross section NN cross section AA cross section AA (pQCD) Parton energy loss  R < 1 at large P t

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 Suppression of High Transverse Momentum Hadrons at RHIC Large transverse momentum hadrons are suppressed in central collisions at RHIC √s nn = 17.3 GeV √s nn = 63 GeV √s nn = 130 GeV by factor ~ in central collisions at RHIC

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 Centrality Dependence of Suppression at RHIC Au+Au 130 GeV Phys. Rev. Lett. 89, (2002) STAR

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 Is Origin of Suppression Initial or Final State? Final state parton energy loss? A + A collisions in medium: gluon saturation? nuclear effects in initial state Initial state no parton energy loss nuclear effects in initial state gluon saturation? p,d + A collisions - no medium Distinguish effects - initial state final state

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 Final State Suppression / Initial State Enhancement! The hadron spectra at RHIC from p-p, Au-Au and d-Au collisions establish existence of a new final-state effect - early parton energy loss – from strongly interacting, dense matter in central Au-Au collisions Au + Au Experimentd + Au Control Experiment Preliminary DataFinal Data

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 Unique to Heavy Ion Collisions! Crucial control measurement using d-Au collisions

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 Extreme Energy Densities! –Au-Au suppression (I. Vitev and M. Gyulassy, hep-ph/ ) –d-Au enhancement (I. Vitev, nucl-th/ ) understood in an approach that combines multiple scattering with absorption in a dense partonic medium  high p T probes require dN g /dy ~ 1100  > 100  0 Au-Au d-Au Au + Au

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 Hard Scattering (Jets & Leading Particles) as a Probe of Dense Matter 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

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 Au+Au Leading Particle (Jet) Azimuthal Correlations Assume: Au+Au event with high p T particle is a superposition of p+p event w. high p T particle + AuAu event w. elliptic flow –v 2 from reaction plane analysis –A from fit in non-jet region (0.75 < |  | < 2.24) Peripheral Au + Au Away-side jet 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) Central Au + Au disappears

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 Use Collision Geometry to Vary Parton Path Length x z y

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 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

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 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

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 Hard Scattering Comments 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

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 Summary - What Have We Learned at RHIC So Far? Quark coalescence /flow  constituent quark degrees of freedom Extreme initial densities –  5 GeV/fm 3  ~ x nuclear density > 15,000 q +  q in final state Equilibrium abundances – Universal hadronization T ~ T crit Rapid u, d, s equilibration near T crit parton E loss – large gluon densities  opaque! Ideal hydro - Early thermalization & quark-gluon EOS Pedestal&flo w subtracted parton E loss – large gluon densities  opaque! Indicates strongly interacting, bulk QCD-matter formed in RHIC collisions PRL (2003) Initial state gluon saturation (color glass condensate?) - forward rapidities  low-x d+Au is suppressed

John Harris (Yale) LHC Conference, Vienna, Austria, 15 July 2004 Still to do! Deconfined QGP?  cc,  bb suppression & melting sequence Strangeness enhancement? Thermalized? Open charm, beauty, multiply-strange baryon production & flow Establish properties of the QCD medium Probe parton E-loss with higher p T triggers, jets,  -jet Flavor dependence of suppression & propagation Light vector mesons (mass and width modifications) Direct Photon Radiation? New phenomena……. LHC! RHIC II! “the adventure continues!”

John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04 Still the beginning