Photon production from an anisotropic quark-gluon plasma

We calculate photon production from a quark-gluon plasma which is anisotropic in momentum space including the Compton scattering, q(q̄)g→q(q̄)γ, and annihilation, qq̄→gγ, processes. We show that for a quark-gluon plasma which has an oblate momentum-space anisotropy, ⟨pL²⟩<⟨pT²⟩, the photon production rate has an angular dependence which is peaked transverse to the beam line. We propose to use the angular dependence of high-energy medium photon production to experimentally determine the degree of momentum-space isotropy of a quark-gluon plasma produced in relativistic heavy-ion collisions.