Numerical study of the Schwinger effect in axion inflation

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.