An improved estimate for the photon rate from lattice QCD - part 2
- Mr. Aman STEINBERG
- Mr. Aman STEINBERG (JGU Mainz)
In order to estimate the photon rate from the Euclidean vector current correlation functions, an inverse problem for the vector-channel spectral function must be solved. We use both a direct model for the spectral function and a model-independent estimate from the Backus-Gilbert method to give a robust estimate for the photon rate at momenta close to its maximum. At low photon momenta, the existence of a narrow diffusion pole in the retarded correlation -- a universal hydrodynamic prediction -- makes the extraction of the photon rate challenging. The results are compared with recent predictions from pure gauge theory and weak-coupling effective theory at two different temperatures.