Equilibrium and non-equilibrium effects in relativistic heavy ion collisions

  • The hypothesis of local equilibrium (LE) in relativistic heavy ion collisions at energies from AGS to RHIC is checked in the microscopic transport model. We find that kinetic, thermal, and chemical equilibration of the expanding hadronic matter is nearly reached in central collisions at AGS energy for t >_ fm/c in a central cell. At these times the equation of state may be approximated by a simple dependence P ~= (0.12-0.15) epsilon. Increasing deviations of the yields and the energy spectra of hadrons from statistical model values are observed for increasing bombarding energies. The origin of these deviations is traced to the irreversible multiparticle decays of strings and many-body (N >_ 3) decays of resonances. The violations of LE indicate that the matter in the cell reaches a steady state instead of idealized equilibrium. The entropy density in the cell is only about 6% smaller than that of the equilibrium state.

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Author:Larissa BravinaORCiDGND, Eugene E. ZabrodinORCiD, Mark I. GorensteinORCiDGND, Steffen A. BassORCiDGND, Mohamed Belkacem, Marcus BleicherORCiDGND, Mathias Brandstetter, Christoph Ernst, Amand FäßlerGND, Walter GreinerGND, Sven SoffORCiD, Horst StöckerORCiDGND, Henning WeberGND
Parent Title (English):talk at Quark Matter '99, Torino, Italy, May 10-14, 1999
Document Type:Preprint
Year of Completion:1999
Year of first Publication:1999
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2005/04/14
Source:http://de.arxiv.org/abs/nucl-th/9907062 , talk at Quark Matter '99, Torino, Italy, May 10-14, 1999
Institutes:Physik / Physik
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik
Licence (German):License LogoDeutsches Urheberrecht