The Fermion Self-Energy during Inflation

TL;DR

This paper calculates the one-loop fermion self-energy in a de Sitter background, revealing quantum effects during inflation that could influence fermion behavior through graviton interactions.

Contribution

It provides a fully renormalized computation of fermion self-energy during inflation, including a noninvariant counterterm due to gauge choice.

Findings

Renormalized fermion self-energy in de Sitter space obtained.

Identification of a noninvariant counterterm due to gauge breaking de Sitter invariance.

Framework established for studying inflation-enhanced quantum effects on fermions.

Abstract

We compute the one loop fermion self-energy for massless Dirac + Einstein in the presence of a locally de Sitter background. We employ dimensional regularization and obtain a fully renormalized result by absorbing all divergences with BPHZ counterterms. An interesting technical aspect of this computation is the need for a noninvariant counterterm owing to the breaking of de Sitter invariance by our gauge condition. Our result can be used in the quantum-corrected Dirac equation to search for inflation-enhanced quantum effects from gravitons, analogous to those which have been found for massless, minimally coupled scalars.