Dilepton emission rates from hot hadronic matter

Abstract

The vacuum polarisation effects from the nucleon sector lead to large medium modifications of the vector meson masses in the Walecka model. With a quantum hadrodynamic framework including the quantum effects, and using a quasiparticle description for quark gluon plasma(QGP), the dilepton emission rate from the hot and dense matter resulting from relativistic nuclear collisions is calculated. Using a model for the fireball evolution which has been shown to reproduce other observables such as charmonium suppression, photon emission and the abundance of hadronic species, we compare with the dilepton invariant mass spectrum measured by the CERES collaboration at CERN SPS. We also compare the results to a previous calculation where the spectral function of a virtual photon (a key ingredient for the emission rate) has been calculated in a chiral SU(3) model.