1. 1 Search for Collective Phenomena Art Poskanzer In honor of Miklos Gyulassy’s 60 th birthday 1995 Not a surprise party History of the Emphasizing Miklos’ Contributions

2. 2 Same Topic 26 Years Ago Nuclear Physics A Volume 400, 23 May 1983, Pages 31-41 Copyright © 1983 Published by Elsevier B.V. Nuclear collisions from AMeV to ATeV: From nuclear to quark matter Miklos Gyulassy N u c l ear Science Division, Lawrence Berkeley Laboratory University of California, Berkeley, CA 94720 USA Opening talk at Nucleus-Nucleus ‘82 at MSU: Gyulassy 1983

3. 3 Collisions of Swiss Watches Poskanzer, CERN colloquium (1980) general negative attitude

4. 4 Flowers Amongst the Weeds At the 2 nd Heavy Ion Summer Study in 1974 Wladek Swiatecki talked about “Clearing the weeds and Getting to the heart of the matter” In the 35 years since there have been a few flowers Swiatecki 1983 to find a flower

5. 5 QM87 Nordkirchen Concluding Remarks by Miklos Gyulassy 22 years ago, it was the most memorable talk I have ever heard

6. 6 Shock Waves - 1959 Annals of Physics 6, 1 (1959) First prediction of collective flow at high energy Angle depends on the speed of sound which depends on the Eq. of State 50 years ago

7. 7 Shock Waves W. Scheid, H. Muller, and W. Greiner, PRL 32, 741 (1974) M.I. Sobel, P.J. Siemens, J.P. Bondorf, and H.A. Bethe, Nucl. Phys. A251, 502 (1975) G.F. Chapline, M.H. Johnson, E. Teller, and M.S. Weiss, PRD 8, 4302 (1973)

8. 8 No Shock Waves H.G. Baumgardt et al., Z. Physik A 273, 359 (1973) Peaks in tracks in AgCl crystals Poskanzer and Greiner 1984 d  /d  reviewed in H.R. Schmidt, Int. J. Mod. Phys. A6, 3865 (1991) GSI-LBL, A.M. Poskanzer et al., PRL 35, 1701 (1975) d  /dΩ

9. 9 Shock Waves Again D.H. Rischke, H. Stoecker, and W. Greiner. PRD 42, 2283 (1990) Flow in conical shock waves Away side jet J. Casalderrey-Solana, E.V. Shuryak, and D. Tracy, arXiv hep-ph/0411315 (2004)

10. 10 STAR Phys. Rev. Lett. 102, 052302 (2009) structures are evidence of conical emission of hadrons correlated with high p ⊥ particles. C. Pruneau, QM06, S671 3-particle correlations No clear evidence for conical emission is observed using cumulates. However, see Ulery and Wang, PRC 79, 024904 (2009) CATHIE-RIKEN Workshop: Critical Assessment of Theory and Experiment on Correlations at RHIC February 25-26, 2009 I think experiments not conclusive

11. 11 Should Not Be Bouras, Molnar, Niemi, Xu, El, Fouchler, Greiner, Rischke, ArXiv:0902.1927 an  /s ratio larger than 0.2 prevents the development of well-defined shock waves on timescales typical for ultrarelativistic heavy-ion collisions.

12. 12 Mach Cones Miklos’ last 10 papers have been on Mach Cones G. Torrieri, B. Betz, J. Noronha, and M. Gyulassy, arXiv:0901.0230 Theory very complicated! J. Noronha, M. Gyulassy, and G. Torrieri, PRL 102, 102301 (2009) Doubts PHENIX results are due to ordinary Mach cones

13. 13 Fireball G.D. Westfall et al., Phys. Rev. Letters 37, 1202 (1976)

14. 14 Homework Problem Assigned by Miklos at the 3 rd Summer Study in 1976 Calculate p spectrum of 250 MeV/A Ne + U Nine solutions submitted Factors of 2 - 5 away from the data “The most successful model in reproducing the gross features of the data is the fireball model”

15. 15 Many Probes abt. 1986 Collective Flow

16. 16 Sphericity Best ellipsoid for each event by diagonalizing kinetic energy flow tensor: pzpz (Beam) Reaction plane x y z ss pypy pxpx P. Danielewicz and M. Gyulassy Phys. Lett. B 129, 283 (1983) M. Gyulassy, K.A. Frankel, and H. Stocker, Phys. Lett. 110B, 185 (1982) Major axis and beam axis determine event plane M. Lisa (1999)

17. 17 Polar Flow Angle Gyulassy: “The only true signature of collective flow is a clear maximum of dN/d cos  away from  = 0” Directed Flow M. Gyulassy, K.A. Frankel, and H. Stocker, Phys. Lett. 110B, 185 (1982) P. Danielewicz and M. Gyulassy, Phys. Lett. 129B, 283 (1983)

18. 18 Discovery of Collective Flow Plastic Ball, Gustafsson et al., PRL 52, 1590 (1984) Non-zero flow angle distribution for Nb, but not Ca dN/dcos  Bevalac 400 MeV/A Directed Flow

19. 19 Squeeze-out bounce squeeze 400 MeV/A Au+Au (MUL 3) Plastic Ball, H.H. Gutbrod et al., Phys. Lett. B216, 267 (1989) Diogene, M. Demoulins et al., Phys. Lett. B241, 476 (1990) Plastic Ball, H.H. Gutbrod et al., PRC 42, 640 (1991) Negative Elliptic Flow

20. 20 Expansion In Plane Hiroshi Masui (2008) spatial anisotropy momentum anisotropy 22 v2v2 Positive Elliptic Flow

21. 21 Discovery of Elliptic Flow at RHIC STAR, K.H. Ackermann et al., PRL 86, 402 (2001) First paper from STAR Dramatic effect: Significant that data approach hydro for central collisions Was not true at lower beam energies hydro predictions peripheral central peak / valley = (1 + 2 v 2 ) / (1 - 2 v 2 ) = 1.8

22. 22 A. Wetzler (2005) Elliptic Flow vs. Beam Energy 25% most central mid-rapidity all v 2 {EP} six decades In-plane elliptic flow squeeze-out bounce-off spinning powerful, widely-used tool, to study EOS of nuclear matter

23. 23 Elliptic Flow Rescattering Converts space to momentum anisotropy Becomes more spherical Self-quenching Early time thermalization v2v2 t (fm/c) Zhang, Gyulassy, Ko, Phys. Lett. B455 (1999) 45 Main contribution to elliptic flow early in the collision

24. 24 quarks mesons baryons plotted vs. trans. kinetic energy PHENIX, PRL 98, 162301 (2007) Scaling with Number of Quarks both axes scaled by number of constituent quarks n q = 2 for mesons n q = 3 for baryons recombination of quarks quarks have v 2 before hadronization STAR, PRL 95, 122301 (2005) S. Voloshin, QM02, 379c (2003) particle mass dependence

25. 25 Eq. event plane resolution root-mean-square mean Fluctuations Data: PHOBOS+ Eq.: Ollitrault, Poskanzer, and Voloshin, QM09, ArXiv

26. 26 Fluctuations and Nonflow Corr. published corrected to Part. Plane Ollitrault, Poskanzer, and Voloshin, QM09, arXiv

27. 27 Correction to Reaction Plane Ollitrault, Poskanzer, and Voloshin, QM09, arXiv Glauber fluctuations CGC fluctuations

28. 28 Shear Viscosity shear viscosity entropy density Conjecture was derived from string theory but has simple interpretation based on the uncertainty principle: Mean free path must be bigger than De Broglie wavelength. Larry McLerran Small shear viscosity means small mean free path, which means strongly coupled Danielewicz and Gyulassy, PRD 31, 53 (1985)

29. 29 Viscous Hydrodynamics Romatschke 2, PRL 99, 172301 (2007) Hydro: viscosity lowers v 2 Data: removing non-flow and fluctuations lowers v 2 Both data and hydro need more work on these effects But approximately at the uncertainty principle value Thus  /s is no more than 5 times bigger than the minimum value STAR, B.I. Abelev et al., arXiv:0801.3466; PRC, submitted (2008) = 1/(4  ) estimated removal of non-flow and fluctuations STAR data non-viscous

30. 30 Future More precise multi-particle v 2 Reaction Plane values For many identified species Quark content Do charm and bottom quarks flow? Equilibration Explain R AA and v 2 at the same time Universal understanding

31. 31 in Hungrey, 2001 Miklos found the flowers amongst the weeds:

32. 32 Miklos 1993 2005