A second look at single-photon production in S + Au collisions at 200 A GeV and implications for quark-hadron phase transition

Abstract

We reanalyze the production of single photons in S+Au collisions at CERN SPS to investigate: (i) the consequences of using a much richer equation of state for hadrons than the one used in an earlier study by us, and (ii) to see if the recent estimates of photon production in quark matter (at two-loop level) by Aurenche, et al. are consistent with the upper limit of the photon production measured by the WA80 group. We find that the data are consistent with a quark-hadron phase transition. The data are also consistent with a scenario where no phase transition takes place, but where the hadronic matter reaches a density of several hadrons per unit volume, which is rather unphysical.