Scalar enhancement of the photon electric field by the tail of the graviton propagator

Abstract

One-graviton-loop corrections to the vacuum polarization on a de Sitter background show two interesting infrared effects: a secular enhancement of the photon electric field strength and a long-range running of the Coulomb potential. We show that the first effect derives solely from the "tail" term of the graviton propagator, but that the second effect does not. Our result agrees with the earlier observation that the secular enhancement of massless fermion mode functions derives solely from the tail term. We discuss the implications this has for the important project of generalizing to quantum gravity the Starobinsky technique for summing the series of leading infrared effects from inflationary quantum field theory.