Numerical study of the Schwinger effect in axion inflation

TL;DR

This paper numerically investigates how the Schwinger effect influences gauge field production during axion inflation, affecting preheating and baryogenesis, and finds that gauge preheating is unlikely but baryogenesis remains feasible.

Contribution

It provides a detailed numerical analysis of the Schwinger effect's impact on gauge field dynamics in axion inflation, revisiting baryogenesis scenarios.

Findings

Gauge preheating is unlikely due to the Schwinger effect.

A viable parameter space exists for baryogenesis despite the Schwinger damping.

The Schwinger effect significantly suppresses gauge field amplification.

Abstract

Previous studies demonstrate that the inflaton, when coupled to the hypercharge Chern-Simons density, can source an explosive production of helical hypermagnetic fields. Then, in the absence of fermion production, those fields have the capability of preheating the Universe after inflation and triggering a successful baryogenesis mechanism at the electroweak phase transition. In the presence of fermion production however, we expect a strong damping of the gauge fields production from the fermion backreaction, a phenomenon called Schwinger effect, thus jeopardizing their original capabilities. Using numerical methods we study the backreaction on the generated gauge fields and revisit the processes of gauge preheating and baryogenesis in the presence of the Schwinger effect. We have found that gauge preheating is very unlikely, while still having a sizable window in the parameter space to achieve the baryon asymmetry of the Universe at the electroweak phase transition.