Speaker
Description
We report the first analytic proof that the intermediate momentum cutoff separating hard and soft contributions to thermal photon production cancels exactly at finite quark chemical potential, previously confirmed only numerically. We identify and resolve an inconsistency in an earlier attempted closed-form hard contribution, thereby arriving at a well-behaved, closed-form, cutoff-independent expression for the total photon rate. This reveals that the widely used Traxler et al. parametrization deviates noticeably from the exact rate, especially at low photon energies and for moderate values of the chemical potential relative to temperature. The result can be readily used in hydrodynamic simulations and is relevant for RHIC's beam-energy-scan program and upcoming FAIR/NICA experiments.