Reheating with effective potentials

We consider reheating for a charged inflaton which is minimally coupled to electromagnetism. The evolution of such an induces time-dependent mass the photon. show how massive photon propagator can be expressed as spatial Fourier mode sum involving three different sorts functions, just like constant case. develop accurate analytic approximations these and use them approximate effective force exerted on $0$-mode. This allows one simply compute $0$-mode follow progress reheating.