Searching for missing direct photons in heavy-ion collisions with P and CP violation

The spectrum of direct photons from the quark-gluon plasma produced at RHIC has defied the efforts of theorists to describe it. In particular, a significant increase in the number of photons produced at low p_T and a non-zero v_2 flow coefficient have yet to be predicted simultaneously. In an attempt to investigate possible solutions, we study synchrotron radiation from massive fermions in a medium with a chiral chemical potential and a chiral gradient parallel to the magnetic field. In the limit of a non-interacting plasma, these parameters increase the number of photons produced at low p_T while suppressing the traditionally large synchrotron radiation flow coefficient v_2 to levels comparable to those seen in experiments. Given these results, we suggest that P- or CP-violating domains, long conjectured to exist in quark-gluon plasma and recently suggested by results from the STAR collaboration, may be a solution to the problem of missing direct photons.