Probing the equation of state in Au+Au at 11 GeV/nucleon with (3+1)-dimensional hydrodynamics

The effect of (i) the phase transition between a quark gluon plasma (QGP) and a hadron gas and (ii) the number of resonance degrees of freedom in the hadronic phase on the single inclusive distributions of 16 different types of produced hadrons for Au+Au collisions at the Brookhaven Alternating Gradient Synchroton (AGS) energies is studied. We have used an exact numerical solution of the relativistic hydrodynamical equations without free parameters which, because of its (3+1)-dimensional character, constitutes a considerable improvement over the classical Landau solution. We assume chemical equilibration and we use two different equations of state (EOS): one describing a phase transition from QGP to the hadronic phase and two versions of a purely hadronic EOS; we find that the first one gives an overall better description of the Au+Au experimental data at AGS energies. We reproduce and analyze measured meson and proton spectra and also make predictions for antiprotons, deltas, antideltas, and hyperons. The low m(t) enhancement in pi(-) spectra is explained by baryon number conservation and strangeness equilibration. The sensitivity of various production channels to the EOS is analyzed.