Equation of State, Spectra and Composition of Hot and Dense Infinite Hadronic Matter in a Microscopic Transport Model ∗

Bogolyubov Institute for Theoretical Physics, Kiev, Ukraine(February 9, 2008)Equilibrium properties of infinite relativistic hadron matter are investi-gated using the Ultrarelativistic Quantum Molecular Dynamics (UrQMD)model. The simulations are performed in a box with periodic boundary con-ditions. Equilibration times depend critically on energy and baryon densities.Energy spectra of various hadronic species are shown to be isotropic andconsistent with a single temperature in equilibrium. The variation of energydensity versus temperature shows a Hagedorn-like behavior with a limitingtemperature of 130±10 MeV. Comparison of abundances of different particlespecies to ideal hadron gas model predictions show good agreement only ifdetailed balance is implemented for all channels. At low energy densities,high mass resonances are not relevant; however, their importance raises withincreasing energy density. The relevance of these different conceptual frame-works for any interpretation of experimental data is questioned.