Dissipative Effects in Photon Diagnostics of Quark Gluon Plasma
  The effects of dissipation on the space time evolution of matter formed in ultra-relativistic heavy ion collision is discussed. The thermal photon spectra for RHIC and LHC energies with viscous flow is considered. The effects of viscosity in the thermal single photon spectra is seen to be important in QGP phase as compared to the hadronic phase. Recently available data from WA80 group at SPS energies for $S+Au$ collision are compared with theoretical calculations. The experimental data do not appear to be compatible with the formation of matter in the pure hadronic phase. 
Sourav Sarkar, Pradip Roy, Jane Alam, Sibaji Raha and Bikash Sinha