Photons from Pb+Pb and S+Au collisions at ultrarelativistic energies - art. no. 054907

The effects of the variation of vector meson masses and decay widths on pho ton production from hot and dense strongly interacting matter formed after S+Au collisions at CERN Super Proton Synchrotron (SPS energies are consider ed. It has been shown that the photon spectra measured by the WA80 Collabor ation cannot distinguish between the formation of quark matter and hadronic matter in the initial state. The photon yield in Pb+Pb collisions at CERN SPS and BNL Relativistic Heavy Ion Collider energies is estimated. [S0556-2 813(99)01711-2].