1. The importance of multiparticle collisions in heavy ion reactions C. Greiner The Physics of High Baryon Density IPHC Strasbourg, Sept. 2006 Johann Wolfgang Goethe-Universität Frankfurt Institut für Theoretische Physik Motivation: chemical equilibration of anti-baryons Equilibration by potential Hagedorn states Thermalization at RHIC by Outlook

2. Exploring the phases of nuclear matter

3. Strangeness production at SpS energies J. Geiss Production of Antihyperons: QGP signature…? P. Koch, B. Müller, J. Rafelski

4. Production of Anti-Baryons R.Rapp and E. Shuryak, Phys.Rev.Lett.86 (2001) 2980 C.Greiner and S.Leupold, J.Phys. G27 (2001) L95 Multimesonic channels

5. C.Greiner, AIP Conf. Proc. 644:337 (2003)

6. production at RHIC I. Shovkovy, J. Kapusta Thermal rates within chiral SU(3) description Chemical population of baryons / anti-baryons: P. Huovinen, J. Kapusta Insufficient by a factor of 3 to 4

7. Chemical Freeze-out and of QCD Hadronic resonance gas vs. lattice: (P. Braun-Munzinger, J. Stachel, C. Wetterich, Phys.Lett.B596:61-69 (2004)) Chemical equilibration of baryon / anti-baryons: Multimesonic channels:

8. Possible solution by Hagedorn states C. Greiner, P. Koch, F. Liu, I. Shovkovy, H. Stöcker J.Phys.G31 (2005)

9. K. Redlich et al, K. Bugaev et al Hagedorn gas close to Hagedorn spectrum: Hagedorn like excitations in transport models: RQMD HSD

10. Estimate for baryon/antibaryon production

11. Microcanonical decay of HS (Fuming Liu)

12. Master Equations for the decay HS→nπ+BaB J. Noronha-Hostler TexPoint fonts used in EMF: AAAAAAA dN R(i) /dt=-  i N R(i) +  n  i,  BaB (T)(N  ) N 2 BaB dN  /dt=  i  n  i,  nB i ! n  (N R(i) - (N R(i) - BaB (T)(N  ) N 2 BaB ) dN BaB /dt=-  i  i,BaB (N BaB 2 N  (T)-N R(i) )

13. Considering the decay HS→nπ

14. HS→nπ+BaB N π (t=0)=Equilibrium N Res (t=0)=0 N π (t=0) =Equilibrium N Res (t=0)=Equilibrium

15. HS→nπ+BaB when the Hagedorn Resonances start at twice equilibrium values and the rest starts at zero.

16. HS→nπ+BaB when the Hagedorn Resonances start at twice equilibrium values and the rest starts at equilibrium.

17. The strange sector of baryons/antibaryons

18. Importance of baryonic HS CBM?

22. The order and shape of QGP phase transition nucl-th/0605052, I. Zakout, CG and J. Schaffner-Bielich density of states:

23. Thermalization at RHIC elliptic flow --- `early signature´ of QGP evidence for an early buildup of pressure and a fast thermalization of the quark-gluon system How can one describe the fast thermalization by the partonic collisions? How can one understand the hydrodynamical behavior by the partonic collisions ? transport simulation: on-shell parton cascade solving the Boltzmann-equations for quarks and gluons new development (Z)MPC, VNI/BMS Z. Xu and C. Greiner, PRC 71, 064901 (2005)

24. Initial production of partons minijets string matter

25. Stochastic algorithm P.Danielewicz, G.F.Bertsch, Nucl. Phys. A 533, 712(1991) A.Lang et al., J. Comp. Phys. 106, 391(1993) for particles in  3 x with momentum p 1,p 2,p 3... collision probability: cell configuration in space 3x3x parton scatterings in leading order pQCD

26. the central region:  : [-0.5:0.5] and x t < 1.5 fm thermalization and hydrodynamical behavior NO thermalization and free streaming including gg  gggwithout gg  ggg

27. transverse energy at y=0 in Au+Au central collision

28. elliptic flow in noncentral Au+Au collisions at RHIC: central peripheral

30. Comparison with RHIC data

32. Conclusions and Outlook Potential Hagedorn states as additional dof can explain and also strange baryon production close to ; (re-)population and decay are governed by detailed balance Three main assumptions: (1): (2): (3): microcanonical statistical decay Multiparticle interactions also important for very high energies ( ) Future: Embedding into UrQMD

33. CERES Nonequilibrium dilepton production Spectral function of the ρ-meson: free ρin-medium → quantum “off-shell”-transport description (B. Schenke)

34. Non-equilibrium dilepton production rate: Evolving spectral function and dilepton rate Contributions to the rate at time τ at constant energy ω B. Schenke, C. Greiner, Phys.Rev.C73:034909 (2006)

35. Dilepton yields from fireball (B. Schenke) Dropping mass scenario integrated over momenta: Dropping mass (linearly in time) and resonance coupling scenarios for k=0: B. Schenke, C. Greiner, Phys.Rev.C73:034909 (2006) B. Schenke, C. Greiner, arXiv:hep-ph/0608032 (2006)