Thermal photon production rate from QGP at finite density: Analytic cutoff independence

Abstract

We compute the thermal photon production rate from a hot and dense quark-gluon plasma. While the mutual cancellation of the intermediate momentum cutoff $k_c$ between the hard and soft regimes in the presence of finite baryon density has been previously established only numerically, we demonstrate here, for the first time, that this cutoff independence can be shown analytically even in the presence of a nonzero quark chemical potential $\mu$. This resolves a long-standing issue addressed in Ref.[1]. The final expression for the photon rate can be treated as a generalization of the results obtained in Refs.[2,3] in the presence of $\mu$ and can be implemented directly in the space-time evolution of a hot and dense QGP medium using relativistic hydrodynamics.