Roy A. Lacey, Stony Brook, ISMD, Krom, Roy A. Lacey What do we learn from Correlation measurements at RHIC Roy A. Lacey, Stony Brook, ISMD, Krom, Motivation Which observables & phenomena connect to the de-confined stage? initial state pre-equilibrium QGP and hydrodynamic expansion hadronization hadronic phase and freeze-out Conjecture of collisions at RHIC : Courtesy S. Bass Roy A. Lacey, Stony Brook, ISMD, Krom, Flow correlations provide an important probe Roy A. Lacey, Stony Brook, ISMD, Krom, squeeze bounce Prologue Low Energy: Squeeze-out High Energy In-plane Do we understand Flow correlations ? Do we understand Flow correlations ? The expected transition Is observed Phys.Rev.Lett.83:1295,1999 Pressure Gradients Drive Transverse and Elliptic flow DATA (KAOS Z. Phys. A355 (1996); (E895) - PRL 83 (1999) 1295 Roy A. Lacey, Stony Brook, ISMD, Krom, What information do Flow correlations provide? What information do Flow correlations provide? Provides reliable estimates of pressure & pressure gradients Can address questions related to thermalization Gives insights on the transverse dynamics of the medium Provides access to the properties of the medium - EOS, sound speed (c s ), viscosity, etc Barometric Sensor: Roy A. Lacey, Stony Brook, ISMD, Krom, In-plane Out-of-plane Correlation Function Harmonic Jet Function Azimuthal Correlations Provide Two Direct routes to the Properties of the High Energy Density Matter Created at RHIC Remarkable Fact Azimuthal Correlations are derived from Harmonic and di-jet contributions There are two sources of azimuthal correlations at RHIC ! Roy A. Lacey, Stony Brook, ISMD, Krom, PRL87, (2001) Central collisions peripheral collisions time to thermalize the system ( 0 ~ fm/c) Bjorken ~ GeV/fm 3 ~ 35 100 0 Extrapolation From E T Distributions The Energy Density is Well Above the Predicted Value for the Phase Transition /crossover ! Phase Transition:Reminder High Energy density matter is created at RHIC! Reminder High Energy density matter is created at RHIC! Roy A. Lacey, Stony Brook, ISMD, Krom, Cu+Cu Preliminary 3-6%, N part = 100 Au+Au 35-40%, N part = 99 Particle production is essentially geometry dominated Un-scaled dN/d Au+Au 35-40%,N part = 98 Cu+Cu Preliminary 3-6%, N part = 96 PHOBOS Data Reminder Particle production & system size Reminder Particle production & system size Roy A. Lacey, Stony Brook, ISMD, Krom, Reminder Statistical Model Comparisons of Particle RatiosReminder Statistical Model Comparisons of Particle Ratios Hadro-chemistry indicates a single Hadronization Temperature ~ 175 MeV Roy A. Lacey, Stony Brook, ISMD, Krom, Substantial elliptic flow signals should be present for a variety of particle species Extrapolation From E T Distributions Is Thermalization Rapid ? Is Thermalization Rapid ? Large Pressure Gradients v 2 Detailed integral and differential Measurements now available for Self quenching Roy A. Lacey, Stony Brook, ISMD, Krom, Large Pressure Gradients are Generated Very Early ! Is Thermalization Rapid ? Is Thermalization Rapid ? PHENIX (open symbols): Phys. Rev. Lett. 91, (2003) STAR preliminary Roy A. Lacey, Stony Brook, ISMD, Krom, v 2 sheet for mesons & Baryons Exquisite Features Due to Radial flow ? Roy A. Lacey, Stony Brook, ISMD, Krom, Heavy quark Thermalization ? Is Thermalization Rapid ? Is Thermalization Rapid ? (Rapp) Roy A. Lacey, Stony Brook, ISMD, Krom, Is the matter unique ? PHENIX preliminary Results are strikingly similar for V 2 decreases by ~ 50% from RHIC to SPS Significantly larger pressure (gradients) at RHIC than at SPS CERES Roy A. Lacey, Stony Brook, ISMD, Krom, Apparent saturation of v2 for Excitation function for differential v 2 Possible indication for a soft EOS ! PHENIX preliminary Roy A. Lacey, Stony Brook, ISMD, Krom, Does the Flow follow ideal hydrodynamics ? Non-trivial issue for EOS, viscosity, etc Investigate Hydrodynamic Scaling Relations for the fine structure of v 2 Investigate Hydrodynamic Scaling Relations for the fine structure of v 2 Fit Data Roy A. Lacey, Stony Brook, ISMD, Krom, Fine Structure Scaling Note Universal Scaling prediction ( WHY ? ) P P Buda Lund Hydro Model nucl-th/ System size independence M. Csaad C. Csrgo et al. Roy A. Lacey, Stony Brook, ISMD, Krom, Scaling Tests Hydro Limit The shape of things to come Eccentricity scaling Roy A. Lacey, Stony Brook, ISMD, Krom, Scaling of azimuthal anisotropy - Mesons PHENIX Preliminary Scaling works over a broad range for charged hadrons and identified particles Roy A. Lacey, Stony Brook, ISMD, Krom, Scaling of azimuthal anisotropy - Hydro Hydro eccentricity scaling Roy A. Lacey, Stony Brook, ISMD, Krom, Scaling of azimuthal anisotropy - system size Scaling of Cu+Cu and Au+Au collisions indicate system size indipendece PHENIX Preliminary Roy A. Lacey, Stony Brook, ISMD, Krom, Unequivocal scaling at low values scaling breaks ~ 1.8 Scaling PHENIX Data PHENIX Preliminary 5