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The importance of multiparticle collisions in heavy ion reactions

Johann Wolfgang Goethe-Universität Frankfurt Institut für Theoretische Physik. The importance of multiparticle collisions in heavy ion reactions. C. Greiner Zimanyi 75 Memorial Workshop Budapest, july 2007. Motivation: chemical equilibrium of anti-baryons

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The importance of multiparticle collisions in heavy ion reactions

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  1. Johann Wolfgang Goethe-Universität Frankfurt Institut für Theoretische Physik The importance of multiparticle collisions in heavy ion reactions C. Greiner Zimanyi 75 Memorial Workshop Budapest, july 2007 • Motivation: chemical equilibrium of anti-baryons • Chemical equilibration at the Hagedorn temperature • Thermalization and viscosity at RHIC by • Outlook

  2. Exploring the phases of nuclear matter

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

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

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

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

  7. Chemical Freeze-out and of QCD (P. Braun-Munzinger, J. Stachel, C. Wetterich,Phys.Lett.B596:61-69 (2004)) Chemical equilibration of baryon / anti-baryons: Hadronic resonance gas vs. lattice: 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 • master equation: J. Noronha-Hostler, C. Greiner, I. A. Shovkovy.

  13. Results: nπ$HS $ nπ • Case 1: Pions are held in equilibrium • Case 2: Hagedorn States are held in equilibrium, when there are no initial pions when they are close to equilibrium

  14. Results: nπ$HS $ nπ • Case 3: Both are out of equilibrium • Quasi-equilibrium is first reached when both the heaviest resonance and the pions have exceeded their respective equilibration times, and τ2GeV~0.2 fm/c and τπ~0.2 to 0.02 fm/c . Full quasi-equilibrium is reached when the lightest resonance reaches quasi-equilibrium i.e. τ7GeV~0.8 fm/c. • Total equilibration time: J. Noronha-Hostler, C. Greiner, I. A. Shovkovy. (In preparation)

  15. Results: nπ $HS $ nπ +

  16. Results: Expansion J. Noronha-Hostler, C. Greiner, I. A. Shovkovy. (In Preparation)

  17. The strange sector of baryons/antibaryons

  18. Importance of baryonicHS CBM?

  19. The order and shape of QGP phase transition I. Zakout, CG and J. Schaffner-Bielich, NPA 781 (2007) 150 density of states:

  20. Relativistic Quantum Transport for URHIC RHIC, LHC • microscopic transport calculations of partonic degrees of freedom new development Boltzmann Approach of MultiParton Scatterings (BAMPS) Z. Xu and C. Greiner, PRC 71, 064901 (2005) collision probability D3x particle in cell method

  21. Initial production of partons minijets string matter

  22. fast isotropization and thermalisation elliptic flow in noncentral Au+Au collisions at RHIC: Z. Xu and C. Greiner, hep-ph/0703233 Z. Xu and C. Greiner, NPA 774, 787 (2006) central hydrodynamical evolution of momentum spectrum, … micr. determination of transport parameter …

  23. Comparison with RHIC data

  24. Evolution of temperature and spectrum with CGC initial condition Andrej El

  25. extracting the viscosity preliminary Bjorken geometry:

  26. Conclusions and Outlook • Potential Hagedorn states as additional dof can explain and also strangebaryon 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

  27. Parameters Branching Ratios using a Gaussian distribution where <n>=0.9+1.2(mi/mp)~3 to 9 and σ2=[0.5(mi/mp)] 2~1 to 12 The decay width is then Γi=0.15mi-60=250 to 1000 MeV <nb>=0.5+0.6(mi/mp)~3 to 6 and Γi,π=Γi-<B>Γi,BB where Γi,BB= <B>Γi. Since <B> ranges from 0.2 to 0.4, Γi,BB is between 50 and 400 MeV. • Bjorken expansion for r0=7.1 and a0=0.05 -F.M. Liu et. al.

  28. parton scatterings in leading order pQCD J.F.Gunion, G.F.Bertsch, Phys. Rev. D 25, 746(1982) screening mass: LPM suppression: the formation time

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