Resumming photon loops for inflationary gravity

A previous calculation of the one-loop photon contribution to the graviton self-energy on the de Sitter background is considered. We first show that there is no local obstacle to conservation, unlike the contribution from a loop of massless, minimally coupled scalars. This is correlated to the absence of an Eddington (${R}^{2}$) counterterm and to the vanishing of the stress tensor when the photon is integrated out in the presence of a constant graviton field. We also show that there is a secularly growing one-loop contribution to the electric components of the Weyl tensor for plane wave gravitons. Its coefficient agrees with that of the secular one-loop correction to the Newtonian potential, and both can be resummed using a variant of the renormalization group.