Phenomenology of collinear photon emission from quark-gluon plasma in $AA$ collisions

We study the role of running coupling and the effect of variation of the thermal quark mass on contribution of the collinear bremsstrahlung and annihilation to photon emission in $AA$ collisions in a scheme similar to that used in our previous jet quenching analyses. We find that for a scenario with the thermal quark mass $m_q\sim 50-100$ MeV contribution of the higher order collinear processes summed with the $2\to 2$ processes can explain a considerable part ($\sim 50$%) of the experimental photon spectrum at $k_T\sim 2-3$GeVforAu+Aucollisionsat$\sqrt{s}=0.2$TeV\mathrm{.}Butfor$m_q=300$ MeV and for the thermal quark mass predicted by the HTL scheme the theoretical predictions underestimate considerably the experimental spectrum.