Thermal Photons and Lepton Pairs from Quark Gluon Plasma and Hot Hadronic Matter

The formulation of the real and virtual photon production rate from strongly interacting matter is presented in the framework of finite temperature field theory. The changes in the hadronic spectral function induced by temperature are discussed within the ambit of the Walecka type model and QCD sum rule approach. Possibility of observing the direct thermal photon and lepton pair from quark gluon plasma has been contrasted with those from hot hadronic matter without and with medium effects for various mass variation scenarios. We note that the in-medium effects on the low invariant mass distribution of dilepton and transverse momentum spectra of photon are conspicuously visible.