dorsal/arxiv
View SchemaLocal Thermodynamical Equilibrium and the Equation of State of Hot, Dense Matter Created in Au+Au Collisions at AGS
| Authors | L. V. Bravina, M. I. Gorenstein, M. Belkacem, S. A. Bass, M. Bleicher, M. Brandstetter, M. Hofmann, S. Soff, C. Spieles, H. Weber, H. Stöcker, W. Greiner |
|---|---|
| Categories | |
| ArXiv ID | nucl-th/9804008 |
| URL | https://arxiv.org/abs/nucl-th/9804008 |
| DOI | 10.1016/S0370-2693(98)00624-8 |
| Journal | Phys.Lett. B434 (1998) 379-387 |
Abstract
Local kinetic and chemical equilibration is studied for Au+Au collisions at 10.7 AGeV in the microscopic Ultrarelativistic Quantum Molecular Dynamics model (UrQMD). The UrQMD model exhibits dramatic deviations from equilibrium during the high density phase of the collision. Thermal and chemical equilibration of the hadronic matter seems to be established in the later stages during a quasi-isentropic expansion, observed in the central reaction cell ($S/A=S/A=s/\rho_B ~\cong~$ 12). At latest stages of the reactions (of order of 10 fm/c) the hadron energy spectra in the cell are nicely reproduced by Boltzmann distributions with a common rapidly dropping temperature. Hadron yields change drastically and at the late expansion stage follow closely those of an ideal gas statistical model. The detailed comparison with the UrQMD box calculations for infinite equilibrated matter is done. It also shows that the system in the central zone reaches the equilibrium at late stages of the reaction. The equation of state seems to be simple at late times: $P\cong0.12\epsilon$ which coincides with Shuryak predictions for the resonance gas. The contribution of the strange particles into the total energy density of the system in the central region of the reaction seems to be of order of 1-3 % (strange particle density in the central zone is negligibly small e.g. $\rho_S=0.008$). The time evolution of other thermodynamical variables in the cell is also presented.
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"abstract": "Local kinetic and chemical equilibration is studied for Au+Au collisions at\n10.7 AGeV in the microscopic Ultrarelativistic Quantum Molecular Dynamics model\n(UrQMD). The UrQMD model exhibits dramatic deviations from equilibrium during\nthe high density phase of the collision. Thermal and chemical equilibration of\nthe hadronic matter seems to be established in the later stages during a\nquasi-isentropic expansion, observed in the central reaction cell\n($S/A=S/A=s/\\rho_B ~\\cong~$ 12). At latest stages of the reactions (of order of\n10 fm/c) the hadron energy spectra in the cell are nicely reproduced by\nBoltzmann distributions with a common rapidly dropping temperature. Hadron\nyields change drastically and at the late expansion stage follow closely those\nof an ideal gas statistical model. The detailed comparison with the UrQMD box\ncalculations for infinite equilibrated matter is done. It also shows that the\nsystem in the central zone reaches the equilibrium at late stages of the\nreaction. The equation of state seems to be simple at late times:\n$P\\cong0.12\\epsilon$ which coincides with Shuryak predictions for the resonance\ngas. The contribution of the strange particles into the total energy density of\nthe system in the central region of the reaction seems to be of order of 1-3 %\n(strange particle density in the central zone is negligibly small e.g.\n$\\rho_S=0.008$). The time evolution of other thermodynamical variables in the\ncell is also presented.",
"arxiv_id": "nucl-th/9804008",
"authors": [
"L. V. Bravina",
"M. I. Gorenstein",
"M. Belkacem",
"S. A. Bass",
"M. Bleicher",
"M. Brandstetter",
"M. Hofmann",
"S. Soff",
"C. Spieles",
"H. Weber",
"H. St\u00f6cker",
"W. Greiner"
],
"categories": [
"nucl-th"
],
"doi": "10.1016/S0370-2693(98)00624-8",
"journal_ref": "Phys.Lett. B434 (1998) 379-387",
"title": "Local Thermodynamical Equilibrium and the Equation of State of Hot, Dense Matter Created in Au+Au Collisions at AGS",
"url": "https://arxiv.org/abs/nucl-th/9804008"
},
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