Quark-gluon plasma versus hadron gas. What one can learn from hadron abundances

Abstract

We use a phenomenological equation of state to describe the phase transition between a hot and dense hadron resonance gas and a quark-gluon plasma. Our analysis covers the entire temperature-baryon density plane. The consequences for the phase diagram of strangeness conservation during nuclear collisions are analyzed. The flavor composition of the quark plasma and an equilibrated hadron resonance gas is studied and compared along the phase transition surface. We emphasize the need to compare systems with equal total baryon number and entropy contents in order to be consistent with the dynamics of the hadronization process and to obtain results relevant to nuclear collisions. From our results we conclude that the flavor composition of the hadronization debris from a quark-gluon plasma formed in a nuclear collision is probably hard to distinguish from that of a chemically equilibrated hadron gas, although in both cases the production level of strange and nonstrange antibaryons will be much higher than observed in proton-proton collisions.