Euclidean correlators at imaginary spatial momentum and their relation to the thermal photon emission rate
Euclidean correlators at imaginary spatial momentum and their relation to the thermal photon emission rate
The photon emission rate of a thermally equilibrated system is determined by the imaginary part of the in-medium retarded correlator of the electromagnetic current transverse to the spatial momentum of the photon. In a Lorentz-covariant theory, this correlator can be parametrized by a scalar function $\mathcal{G}_R(u\cdot \mathcal{K},\mathcal{K}^{2})$, where u is …