Photon production from a non-equilibrium quark-gluon plasma

TL;DR

This paper calculates photon production from a non-equilibrium quark-gluon plasma using anisotropic hydrodynamics, highlighting the sensitivity of high-energy photon yields to initial momentum-space anisotropy and suggesting experimental constraints.

Contribution

It introduces a self-consistent method to include non-equilibrium effects in photon rate calculations within anisotropic hydrodynamics.

Findings

High-energy photon production is sensitive to initial momentum-space anisotropy.

Predictions for photon spectrum and elliptic flow as functions of shear viscosity.

Potential to constrain early-time quark-gluon plasma anisotropy experimentally.

Abstract

We calculate leading-order medium photon yields from a quark-gluon plasma using (3+1)-dimensional anisotropic hydrodynamics. Non-equilibrium corrections to the photon rate are taken into account using a self-consistent modification of the particle distribution functions and the corresponding anisotropic hard-loop fermionic self-energies. We present predictions for the high-energy photon spectrum and photon elliptic flow as a function of transverse momentum, shear viscosity, and initial momentum-space anisotropy. Our findings indicate that high-energy photon production is sensitive to the assumed level of initial momentum-space anisotropy of the quark-gluon plasma. As a result, it may be possible to experimentally constrain the early-time momentum-space anisotropy of the quark-gluon plasma generated in relativistic heavy-ion collisions using high-energy photon yields.