DINESH KUMAR SRIVASTAVA

Physics Group, Variable Energy Cyclotron Centre, 1/AF, Bidhan Nagar, Kolkata 700 064, India

The production of single photons in Pb+Pb collisions at the CERN SPS as measured by the WA98 experiment is analysed. A quark gluon plasma is assumed to be formed initially, which expands, cools, hadronizes, and undergoes freeze-out. A rich hadronic equation of state is used and the transverse expansion of the interacting system is taken into account. The recent estimates of photon production in quark-matter (at two loop level) along with the dominant reactions in the hadronic matter leading to photons are used. About half of the radiated photons are seen to have a thermal origin. The same treatment and the initial conditions provide a very good description to hadronic spectra measured by several groups and the intermediate mass dileptons measured by the NA50 experiment, lending a strong support to the conclusion that quark gluon plasma has been formed in these collisions. Predictions for RHIC and LHC energies are also given.

Keywords:  Quantum chromodynamics; quark-gluon plasma; relativistic heavy ion collisions; photon; dilepton; hadron; transverse momentum; phase transition; charm.

Pacs Nos.  25.75.-q