The Role of Strangeness in the Hadronization of the Quark-Gluon Plasma.

Strangeness in the evolution of a quark-gluon plasma is considered. A phenomenological equation of state is used to describe the phase transition between a hot and dense hadron gas and a quark-gluon plasma. The consequences for the phase diagram of strangeness conservation during nuclear collisions are analyzed. The flavour composition of the quark plasma and an equilibrated hadron gas is studied and compared along the phase transition surface. Our analysis covers the entire temperature-baryon density plane. When the systems of equal entropy contents are compared, the chemical composition of the hadronization debris from a quark-gluon plasma is similar to that of a chemically equilibrated hadron gas, although in both cases the production level of strange and non-strange antibaryons will be much higher than in observed in proton-proton collisions. Using a schematic hydrodynamic description of relativistic heavy-ion collisions in the regime of complete nuclear stopping, we study the freeze-out and strange particle energy spectra from a hadronized quark-gluon plasma. Characteristic changes in the slopes of the K^+ and K^- meson energy spectra are found and suggested as a signature for the quark-gluon plasma phase transition.