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

Abstract

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 ∼ 50−100 MeV contribution of the higher order collinear processes summed with the 2 → 2 processes can explain a considerable part (∼50%) of the experimental photon spectrum at k_T ∼ 2–3 GeV for Au+Au collisions at \(\sqrt s \)= 0.2 TeV. However, for m_q = 300 MeV and for the thermal quark mass predicted by the HTL scheme the theoretical predictions underestimate considerably the experimental spectrum.