1. Roy A. Lacey, Stony Brook, ISMD, Kromĕříž, 2005 1 Roy A. Lacey What do we learn from Correlation measurements at RHIC

2. Roy A. Lacey, Stony Brook, ISMD, Kromĕříž, 2005 2 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

3. Roy A. Lacey, Stony Brook, ISMD, Kromĕříž, 2005 3 Flow correlations provide an important probe

4. Roy A. Lacey, Stony Brook, ISMD, Kromĕříž, 2005 4 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

5. Roy A. Lacey, Stony Brook, ISMD, Kromĕříž, 2005 5 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”:

6. Roy A. Lacey, Stony Brook, ISMD, Kromĕříž, 2005 6 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 !

7. Roy A. Lacey, Stony Brook, ISMD, Kromĕříž, 2005 7 PRL87, 052301 (2001) Central collisions peripheral collisions time to thermalize the system (  0 ~ 0.2 - 1 fm/c)  Bjorken  ~ 5 - 15 GeV/fm 3 ~ 35 – 100 ε 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!

8. Roy A. Lacey, Stony Brook, ISMD, Kromĕříž, 2005 8 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

9. Roy A. Lacey, Stony Brook, ISMD, Kromĕříž, 2005 9 Reminder Statistical Model Comparisons of Particle RatiosReminder Statistical Model Comparisons of Particle Ratios Hadro-chemistry indicates a single Hadronization Temperature ~ 175 MeV

10. Roy A. Lacey, Stony Brook, ISMD, Kromĕříž, 2005 10 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

11. Roy A. Lacey, Stony Brook, ISMD, Kromĕříž, 2005 11 Large Pressure Gradients are Generated Very Early ! Is Thermalization Rapid ? Is Thermalization Rapid ? PHENIX (open symbols): Phys. Rev. Lett. 91, 182301 (2003) STAR preliminary

12. Roy A. Lacey, Stony Brook, ISMD, Kromĕříž, 2005 12 v 2 sheet for mesons & Baryons Exquisite Features Due to Radial flow ?

13. Roy A. Lacey, Stony Brook, ISMD, Kromĕříž, 2005 13 Heavy quark Thermalization ? Is Thermalization Rapid ? Is Thermalization Rapid ? (Rapp)

14. Roy A. Lacey, Stony Brook, ISMD, Kromĕříž, 2005 14 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

15. Roy A. Lacey, Stony Brook, ISMD, Kromĕříž, 2005 15 Apparent saturation of v2 for Excitation function for differential v 2 Possible indication for a soft EOS ! PHENIX preliminary

16. Roy A. Lacey, Stony Brook, ISMD, Kromĕříž, 2005 16 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

17. Roy A. Lacey, Stony Brook, ISMD, Kromĕříž, 2005 17 Fine Structure Scaling Note Universal Scaling prediction ( WHY ? ) P P Buda Lund Hydro Model nucl-th/0310040 System size independence M. Csańad C. Csörgo et al.

18. Roy A. Lacey, Stony Brook, ISMD, Kromĕříž, 2005 18 Scaling Tests Hydro Limit The shape of things to come Eccentricity scaling

19. Roy A. Lacey, Stony Brook, ISMD, Kromĕříž, 2005 19 Scaling of azimuthal anisotropy - Mesons PHENIX Preliminary  Scaling works over a broad range for charged hadrons and identified particles

20. Roy A. Lacey, Stony Brook, ISMD, Kromĕříž, 2005 20 Scaling of azimuthal anisotropy - Hydro Hydro eccentricity scaling

21. Roy A. Lacey, Stony Brook, ISMD, Kromĕříž, 2005 21 Scaling of azimuthal anisotropy - system size Scaling of Cu+Cu and Au+Au collisions indicate system size indipendece PHENIX Preliminary

22. Roy A. Lacey, Stony Brook, ISMD, Kromĕříž, 2005 22  Unequivocal scaling at low values  scaling breaks ~ 1.8 Scaling PHENIX Data PHENIX Preliminary 5<Centrality<30 %

23. Roy A. Lacey, Stony Brook, ISMD, Kromĕříž, 2005 23 Scaling of azimuthal anisotropy - hadrons Integral flow scaling observed across

24. Roy A. Lacey, Stony Brook, ISMD, Kromĕříž, 2005 24  Demonstration of higher harmonic scaling Scaling of RHIC data

25. Roy A. Lacey, Stony Brook, ISMD, Kromĕříž, 2005 25  Demonstration of Comprehensive scaling at RHIC Scaling breaks Scaling of RHIC data

26. Roy A. Lacey, Stony Brook, ISMD, Kromĕříž, 2005 26 Quark number scaling -- Partonic Flow ? Quark number scaling -- Partonic Flow ? Hadronic re-scattering does not support observed Phi flow ! baryons mesons Ξ+ΞΩ+ΩΞ+ΞΩ+Ω 200 GeV Au+Au STAR preliminary 200 GeV Au+Au

27. Roy A. Lacey, Stony Brook, ISMD, Kromĕříž, 2005 27 Extended Fine Structure scaling Universal scaling prediction! PHENIX Preliminary 5<Centrality<30 % All Flow Data Now Understood

28. Roy A. Lacey, Stony Brook, ISMD, Kromĕříž, 2005 28 Scaling of azimuthal anisotropy - Hydro Estimate cs !

29. Roy A. Lacey, Stony Brook, ISMD, Kromĕříž, 2005 29  Fits to the data can provide estimates of the properties of the produced matter Initial Foray

30. Roy A. Lacey, Stony Brook, ISMD, Kromĕříž, 2005 30 Correlation measurements give compelling evidence for the production of strongly interacting high energy density partonic matter in RHIC collisions. y x High Density Thermalized partonic material formed early Hard Scattered Partons Traverse rapidly expanding partonic material  Jet-modification (early) & v2  Jet-modification (early) & v2 EpilogueEpilogue sQGP