1. PHOBOS WHITE PAPER REPORT Wit Busza on behalf of the PHOBOS Collaboration White paper report, June 2004

2. We have discovered a strongly interacting medium with extremely high energy density whose description in terms of simple hadronic degrees of freedom is not appropriate; Furthermore, we have discovered that much of the data can be expressed in terms of simple scaling rules which suggest the existence of strong global constraints or some kind of universality in the mechanism of the production of hadrons in high energy collisions (possible connection to ideas of parton saturation) To date, in Heavy Ion Collisions, there is no evidence for the weakly interacting QGP, as naively imagined by a large segment of the community before RHIC turn-on and concluded from a possible misinterpretation of the lattice results (80% of Stefan-Boltzmann is not weakly interacting)

3. …Key early PHOBOS observation…

4. Particle Density near Mid-Rapidity PRL 88, 22302 (2002) PRL 91, 052303 (2003) PRL 85, 3100 (2000) Models prior to RHIC arXiv:nucl-ex/0405027

5. Initially released energy per unit volume > few GeV/fm 3 Note: energy density inside proton ≈ 0.5 GeV/fm 3 Energy per unit volume: Therefore total energy released in |  | < 1 is ~2000GeV Number of Particles Produced at y=0 Energy of Collision dN ch /d  “ relevant” initial volume ~  R 2 X (0.1fm - few fm) X 2 ~ 0.7 GeV Data from: PRL 85, 3100 (2000); PRL 88, 22302 (2002); PRL 91, 052303 (2003); arXiv:nucl-ex/0405027

6. In Au+Au Collisions at  s NN = 200 GeV Maximum released energy is at mid-rapidity In a system at rest with the center of mass Energy/volume > few GeV/fm 3 It is not appropriate to describe such a system in terms of simple hadronic degrees of freedom

7. AT MID-RAPIDITY THE SYSTEM IS RELATIVELY BARYON-FREE PRC 67, 021901R (2003)

8. …The high energy system is strongly interacting…

9. Evidence from flow: 200 GeV Au+Au PHOBOS preliminary 0 <  < 1.5 0-55% central, h + + h - PRL 89, 222301 (2002) Nucl. Phys. A715, 611c (2003)

10. Evidence from the small number of particles produced with very low p T : In a large volume, weakly interacting system you would expect the development of particles with long wavelength arXiv:nucl-ex/0401006 PHOBOS PHENIX

11. Evidence from the suppression of high-p T particles: Au+Au 0-6% 200 GeV PHOBOS d+Au 200 GeV PRL 91, 072302 (2003)

12. STAR BACK-TO-BACK “JET” CORRELATIONS PRL 90, 082302 (2003)

13. Discovery of simple scaling rules… …in other words, discovery of global constraints

14. DISCOVERY OF SIMPLE SCALING BEHAVIORS UNIVERSAL TOTAL PARTICLE PRODUCTION ABSENCE OF BOOST INVARIANT CENTRAL PLATEAU UNIVERSAL SCALING ACCORDING TO “LIMITING FRAGMENTATION” UNIVERSAL N part SCALING FACTORIZATION INTO GEOMETRIC PART AND ENERGY PART

15. UNIVERSAL TOTAL PARTICLE PRODUCTION

16. Brenner et al In pp collisions, on average, approximately half the energy goes into the leading baryon A.Brenner et a., Phys.Rev.D26 (1982) 1497l Relevant energy for comparisons of Au+Au, p+p, and d+Au arXiv:nucl-ex/0301017 arXiv:nucl-ex/0403033

17. arXiv:nucl-ex/0301017

18. ABSENCE OF BOOST INVARIANT CENTRAL PLATEAU

19. E895 3.0 GeV Au+Au BRAHMS prel. NA49 3.6 GeV Au+Au 4.1 GeV Au+Au 8.8 GeV Pb+Pb 17.3 GeV Pb+Pb 200 GeV Au+Au PHOBOS Plateau in pseudorapidity distributions is misleading Rapidity distributions of pions are gaussians PRL 91, 052303 (2003) arXiv:nucl-ex/0403050

20. PHOBOS Preliminary v 2 200 PHOBOS v 2 130 No boost-invariant central plateau for v 2 PRL 89, 222301 (2002)

21. UNIVERSAL SCALING ACCORDING TO “LIMITING FRAGMENTATION”

22. 6% central Au+Au dN ch /d  / /2 PRL 91, 052303 (2003)

23. Rest frame of ARest frame of p or d PHOBOS arXiv:nucl-ex/0403033

25. To be submitted PRL June 2004 Energy and pseudorapidity dependence of v 2

26. To be submitted PRL June 2004 Limiting fragmentation seen in v 2

27. Elliptic flow: To see the limiting behavior, imagine that RHIC collided beams with asymmetric energy, with  ´ = -2 corresponding to y = 0. PRL 91, 052303 (2003)

28. Universal N part scaling

29. N part scaling for:  pA, dA, AA 10 GeV to 200 GeV N part from 2 to 350 E178: J.E.Elias et al., Phys.Rev.D22(1980) 13 arXiv:nucl-ex/0403033 Phobos and E178 data Preliminary pp chosen to have the same available energy

30. FACTORIZATION INTO GEOMETRIC PART AND ENERGY PART

31. Preliminary arXiv:nucl-ex/0403033

32. Example of factorization into geometric part and energy part: arXiv:nucl-ex/0403033 SAME SEEN IN p+A AT ALL ENERGIES

33. Nucl.Phys. A715 (2003) 65-74 PRL 91, 052303 (2003) Phobos

34. Centrality Dependence at |  < 1 PRC 65, 061901R (2002) arXiv:nucl-ex/0405027 Ratio of 200/130 and 200/19.6

35. Energy and geometry factorize arXiv:nucl-ex/0405003

36. We have discovered a strongly interacting medium with extremely high energy density whose description in terms of simple hadronic degrees of freedom is not appropriate; Furthermore, we have discovered that much of the data can be expressed in terms of simple scaling rules which suggest the existence of strong global constraints or some kind of universality in the mechanism of the production of hadrons in high energy collisions To date, in Heavy Ion Collisions, there is no evidence for the weakly interacting QGP, as naively imagined by a large segment of the community before RHIC turn-on and concluded from a possible misinterpretation of the lattice results (80% of Stefan-Boltzmann is not weakly interacting)

37. WE DO NOT CLAIM THE FOLLOWING: Phenomena unique to RHIC - could be similar to the story of jets Color deconfinement - exact nature of system unknown Chiral symmetry restoration

38. SPARES

39. Birger Back, Mark Baker, Maarten Ballintijn, Donald Barton, Russell Betts, Abigail Bickley, Richard Bindel, Wit Busza (Spokesperson), Alan Carroll, Zhengwei Chai, Patrick Decowski, Edmundo García, Tomasz Gburek, Nigel George, Kristjan Gulbrandsen, Clive Halliwell, Joshua Hamblen, Adam Harrington, Michael Hauer, Conor Henderson, David Hofman, Richard Hollis, Roman Holynski, Burt Holzman, Aneta Iordanova, Jay Kane, Nazim Khan, Piotr Kulinich, Chia Ming Kuo, Willis Lin, Steven Manly, Alice Mignerey, Gerrit van Nieuwenhuizen, Rachid Nouicer, Andrzej Olszewski, Robert Pak, Inkyu Park, Heinz Pernegger, Corey Reed, Christof Roland, Gunther Roland, Joe Sagerer, Helen Seals, Iouri Sedykh, Wojtek Skulski, Chadd Smith, Maciej Stankiewicz, Peter Steinberg, George Stephans, Andrei Sukhanov, Marguerite Belt Tonjes, Adam Trzupek, Carla Vale, Sergei Vaurynovich, Robin Verdier, Gábor Veres, Peter Walters, Edward Wenger, Frank Wolfs, Barbara Wosiek, Krzysztof Wozniak, Alan Wuosmaa, Bolek Wyslouch ARGONNE NATIONAL LABORATORYBROOKHAVEN NATIONAL LABORATORY INSTITUTE OF NUCLEAR PHYSICS PAN, KRAKOWMASSACHUSETTS INSTITUTE OF TECHNOLOGY NATIONAL CENTRAL UNIVERSITY, TAIWANUNIVERSITY OF ILLINOIS AT CHICAGO UNIVERSITY OF MARYLANDUNIVERSITY OF ROCHESTER Collaboration (May 2004)

40. dN/d  UA5

41. In a wide variety of systems (hadron + A to A+A) the total number of emitted charged particles appears to scale linearly with the number of participants. The total multiplicity of charged particles emitted in hadron +A is equal to the number of participants times the multiplicity observed in p+p, while in A+A, the constant of proportionality is the multiplicity produced in e+e- annihilations or in p+p at twice the center of mass energy. This is suggestive of a universal energy dependence of charged particle multiplicities in strong interactions. In the forward region, the pseudorapidity densities, when measured as a function of the shifted variable eta’=eta-ybeam appear not to depend on beam energy. The precise form of the distribution depends on the impact parameter, but again in an energy- independent way. No evidence is seen for a boost invariant central plateau.