Single Photons from S + Au Collisions at the CERN Super Proton Synchrotron and the Quark-Hadron Phase Transition

Abstract
The preliminary results for the single-photon spectrum obtained by the WA80 collaboration are analyzed. The data are well described by a scenario where a thermalized quark-gluon plasma is formed initially, which expands, cools, hadronizes, and undergoes a freeze-out. It is also seen that the data do not seem to favor the scenario where the matter is initially formed in a hot hadronic phase, which cools and undergoes freeze-out and does not involve a phase transition.