Quark-gluon plasma in Pb-Pb 158 A GeV collisions: Evidence from strange particle abundances and the Coulomb effect

The hadronic particle production data from relativistic nuclear Pb-Pb 158 A GeV collisions are successfully described within the chemical nonequilibri um model, provided that the analysis treats Omega and <(Omega)over bar> abu ndances with care. We further show that there is a subtle influence of the Coulomb potential on strange quarks in quark matter which is also seen in o ur data analysis, and this Coulomb effect confirms the finding made by chem ical analysis in the S-Au/W/Pb 200 A GeV collisions that the hadron particl e source is deconfined with respect to strange quark propagation. Physical freeze-out conditions (pressure, specific energy, entropy, and strangeness) are evaluated and considerable universality of hadron freeze-out between t he two different collision systems is established.