Resumming Fermion Loops for Inflationary Gravity

TL;DR

This paper calculates quantum corrections from massless fermion loops to gravity during inflation, providing insights into quantum effects on gravitational waves and the response to mass in a de Sitter universe.

Contribution

It introduces a method to compute and sum 1-loop fermion contributions to the graviton self-energy on a cosmological background, advancing understanding of quantum gravity during inflation.

Findings

Quantum corrections modify gravitational wave propagation.

Renormalization group sums corrections over the inflationary period.

Results applicable to quantum effects in early universe cosmology.

Abstract

We compute the 1-loop contribution to the graviton self-energy from a loop of massless fermions on a general cosmological background. The result is used to quantum-correct the linearized Einstein equation on de Sitter background and work out 1-loop corrections to gravitational radiation and to the response to a point mass. The renormalization group is employed to sum these to all orders for as long as the de Sitter phase persists.