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

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 $(P,\epsilon )$-plane has a very simple form, $P=0.15\epsilon$. 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.

Talk at the conference Strangeness'2000, to be published in J. of Phys. G

References in corpus (3)

• Relativistic Hadron-Hadron Collisions in the Ultra-Relativistic Quantum Molecular Dynamics Model (UrQMD)
• Excitation functions of hadronic observables from SIS to RHIC energies
• Aspects of thermal and chemical equilibration of hadronic matter

Cited by in corpus (5)

• Microscopic models and effective equation of state in nuclear collisions at FAIR energies
• Violation of energy-per-hadron scaling in a resonance matter
• Analysis of particle production in ultra-relativistic heavy ion collisions within a two-source statistical model
• Hadronic Entropy Enhancement and Low Density QGP
• Strangeness production in heavy ion collisions at SPS and RHIC within two-source statistical model