When does the Schwinger Preheating Occur?

TL;DR

This paper investigates the conditions under which Schwinger preheating occurs during inflation, using numerical and analytical methods to analyze electric field behavior in specific inflation models.

Contribution

It introduces a hydrodynamic approach to study Schwinger preheating and derives a general attractor solution for electric fields during inflation.

Findings

Schwinger preheating occurs in the kinetic coupling model with sufficient inflaton-photon coupling.

Preheating is not observed in the anisotropic inflation model.

The occurrence depends on whether electric fields reach the attractor during inflation.

Abstract

When the inflaton couples to photons and amplifies electric fields, charged particles produced via the Schwinger effect can dominate the universe after inflation, which is dubbed as the Schwinger preheating. Using the hydrodynamic approach for the Boltzmann equation, we numerically study two cases, the Starobinsky inflation model with the kinetic coupling and the anisotropic inflation model. The Schwinger preheating is not observed in the latter model but occurs for a sufficiently large inflaton-photon coupling in the first model. We analytically address its condition and derive a general attractor solution of the electric fields. The occurrence of the Schwinger preheating in the first model is determined by whether the electric fields enter the attractor solution during inflation or not.