Latest documents http://publikationen.ub.uni-frankfurt.de/index/index/ Fri, 29 Apr 2011 15:27:17 +0200 Fri, 29 Apr 2011 15:27:17 +0200 http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/17226 We study the kinetic and chemical equilibration in 'infinite' parton-hadron matter within the Parton-Hadron-String Dynamics transport approach, which is based on a dynamical quasiparticle model for partons matched to reproduce lattice-QCD results – including the partonic equation of state – in thermodynamic equilibrium. The 'infinite' matter is simulated within a cubic box with periodic boundary conditions initialized at different baryon density (or chemical potential) and energy density. The transition from initially pure partonic matter to hadronic degrees of freedom (or vice versa) occurs dynamically by interactions. Different thermody-namical distributions of the strongly-interacting quark-gluon plasma (sQGP) are addressed and discussed. Vitalii Ozvenchuk; Elena L. Bratkovskaya; Olena Linnyk; Mark I. Gorenstein; Wolfgang Cassing article http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/17226 Fri, 29 Apr 2011 15:27:17 +0200 http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/16301 The multiplicity fluctuations in A+A collisions at SPS and RHIC energies are studied within the HSD transport approach. We find a dominant role of the fluctuations in the nucleon participant number for the final fluctuations. In order to extract physical fluctuations one should decrease the fluctuations in the participants number. This can be done considering very central collisions. The system size dependence of the multiplicity fluctuations in central A+A collisions at the SPS energy range – obtained in the HSD and UrQMD transport models – is presented. The results can be used as a ‘background’ for experimental measurements of fluctuations as a signal of the critical point. Event-by-event fluctuations of the K/p , K/p and p/p ratios in A+A collisions are also studied. Event-by-event fluctuations of the kaon to pion number ratio in nucleus-nucleus collisions are studied for SPS and RHIC energies. We find that the HSD model can qualitatively reproduce the measured excitation function for the K/p ratio fluctuations in central Au+Au (or Pb+Pb) collisions from low SPS up to top RHIC energies. The forward-backward correlation coefficient measured by the STAR Collaboration in Au+Au collisions at RHIC is also studied. We discuss the effects of initial collision geometry and centrality bin definition on correlations in nucleus-nucleus collisions. We argue that a study of the dependence of correlations on the centrality bin definition as well as the bin size may distinguish between these ‘trivial’ correlations and correlations arising from ‘new physics’. 5th International Workshop on Critical Point and Onset of Deconfinement - CPOD 2009, June 08 - 12 2009 Brookhaven National Laboratory, Long Island, New York, USA Volodymyr P. Konchakovski; Michael Hauer; Mark I. Gorenstein; Elena L. Bratkovskaya article http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/16301 Wed, 06 Apr 2011 17:01:22 +0200 http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/2688 In the framework of relativistic quantum molecular dynamics the authors find that the pion system produced in central heavy-ion collisions at Elab/A approximately 1 GeV/nucl. is out of chemical equilibrium. Pion chemical potential is large and decreases during the expansion stage. Debades Bandyopadhyay; Mark I. Gorenstein; Horst Stöcker; Walter Greiner; Heinz Sorge article http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/2688 Mon, 29 May 2006 09:02:05 +0200 http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/2703 The authors formulate a phenomenological extension of the mean-field theory approach and define a class of thermodynamically self-consistent equations of state for nuclear matter. A new equation of state of this class is suggested and examined in detail. Mark I. Gorenstein; Dirk-Hermann Rischke; Horst Stöcker; Walter Greiner; Kyrill A. Bugaev article http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/2703 Fri, 26 May 2006 14:59:04 +0200 http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3108 Abstract: Local thermal and chemical equilibration is studied for central AqA collisions at 10.7 160 AGeV in the Ultrarelativis- . tic Quantum Molecular Dynamics model UrQMD . The UrQMD model exhibits strong deviations from local equilibrium at the high density hadron string phase formed during the early stage of the collision. Equilibration of the hadron resonance matter is established in the central cell of volume Vs125 fm3 at later stages, tG10 fmrc, of the resulting quasi-isentropic expansion. The thermodynamical functions in the cell and their time evolution are presented. Deviations of the UrQMD quasi-equilibrium state from the statistical mechanics equilibrium are found. They increase with energy per baryon and lead to a strong enhancement of the pion number density as compared to statistical mechanics estimates at SPS energies. PACS: 25.75.-q; 24.10.Lx; 24.10.Pa; 64.30.qt Larissa V. Bravina; Mark I. Gorenstein; Eugene E. Zabrodin; Steffen A. Bass; Mohamed Belkacem; Marcus Bleicher; Mathias Brandstetter; Markus Hofmann; Sven Soff; Christian Spieles; H. Weber; Horst Stöcker; Walter Greiner article http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3108 Wed, 07 Dec 2005 13:22:18 +0100 http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3273 We consider the production of the open charm and J/psi mesons in heavy-ion collisions at BNL RHIC. We discuss several recently developed pictures for J/psi production and argue that a measurement at RHIC energies is crucial for disentangling these different descriptions. Mark I. Gorenstein; Andriy P. Kostyuk; Larry McLerran; Horst Stöcker; Walter Greiner article http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3273 Wed, 16 Nov 2005 11:21:28 +0100