de Sitter at all loops: the story of the Schwinger model

TL;DR

This paper provides an exact, non-perturbative analysis of the Schwinger model in de Sitter space, revealing late-time quantum effects, resummation of logarithms, and non-perturbative phenomena.

Contribution

It offers the first exact solution of the Schwinger model in de Sitter space, analyzing correlation functions and comparing non-perturbative results with perturbative predictions.

Findings

Verification of one-loop fermion two-point function matches exact solution

Identification of late-time logarithms and their resummation

Discovery of Boltzmann suppressed non-perturbative effects

Abstract

We consider the two-dimensional Schwinger model of a massless charged fermion coupled to an Abelian gauge field on a fixed de Sitter background. The theory admits an exact solution, first examined by Jayewardena, and can be analyzed efficiently using Euclidean methods. We calculate fully non-perturbative, gauge-invariant correlation functions of the electric field as well as the fermion and analyze these correlators in the late-time limit. We compare these results with the perturbative picture, for example by verifying that the one-loop contribution to the fermion two-point function, as predicted from the exact solution, matches the direct computation of the one-loop Feynman diagram. We demonstrate many features endemic of quantum field theory in de Sitter space, including the appearance of late-time logarithms, their resummation to de Sitter invariant expressions, and Boltzmann suppressed non-perturbative phenomena, with surprising late-time features.