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Transition to resonance-rich matter in heavy ion collisions at RHIC energies

L. V. Bravina·E. E. Zabrodin·M. Bleicher·S. A. Bass·M. Brandstetter·A. Faessler·C. Fuchs·W. Greiner·M. I. Gorenstein·S. Soff·H. Stoecker
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Abstract

The equilibration of hot and dense nuclear matter produced in the central region in central Au+Au collisions at $\sqrt{s}=200$ AGeV is studied within the microscopic transport model UrQMD. The pressure here becomes isotropic at $t \approx 5$ fm/c. Within the next 15 fm/c the expansion of the matter proceeds almost isentropically with the entropy per baryon ratio $S/A \approx 150$. During this period the equation of state in the $(P,ε)$-plane has a very simple form, $P=0.15 ε$. Comparison with the statistical model (SM) of an ideal hadron gas reveals that the time of $\approx 20$ fm/$c$ may be too short to attain the fully equilibrated state. Particularly, the fractions of resonances are overpopulated in contrast to the SM values. The creation of such a long-lived resonance-rich state slows down the relaxation to chemical equilibrium and can be detected experimentally.

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L. V. Bravina, E. E. Zabrodin, M. Bleicher, S. A. Bass, M. Brandstetter, A. Faessler, C. Fuchs, W. Greiner, M. I. Gorenstein, S. Soff, H. Stoecker. 2000-10-26. Transition to resonance-rich matter in heavy ion collisions at RHIC energies. https://doi.org/10.1088/0954-3899%2F27%2F3%2F321

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