Lattice constraints on the thermal photon rate

Understand

We estimate the photon production rate from an SU(3) plasma at temperatures of about 1.1Tc and 1.3Tc.

• Lattice results for the vector current correlator at spatial momenta k ~ (2-6)T are extrapolated to the continuum limit and analyzed with the help of a polynomial interpolation for the corresponding spectral function, which vanishes at zero frequency and matches to high-precision perturbative results at large invariant masses.
• For small invariant masses the interpolation is compared with the NLO weak-coupling result, hydrodynamics, and a holographic model.
• At vanishing invariant mass we extract the photon rate which for k \gsim 3T is found to be close to the NLO weak-coupling prediction.