No-go theorem of anisotropic inflation via Schwinger mechanism

TL;DR

This paper demonstrates that the Schwinger mechanism prevents sustained anisotropic inflation driven by electric fields in models with dilatonic coupling, establishing a no-go theorem.

Contribution

It introduces charged, massive, conformally coupled fields into anisotropic inflation models and proves that pair production induces a damping effect on electric fields, ruling out persistent anisotropic inflation.

Findings

Electric fields decay to zero due to pair production

Damped oscillation of electric fields regardless of charged particle masses

Establishment of a no-go theorem for anisotropic inflation via Schwinger mechanism

Abstract

In the presence of a dilatonic coupling between an inflaton and a $U(1)$ gauge field, a persistent electric field (i.e., an anisotropic inflation) is obtained as a solution of the classical field equations. We introduce charged, massive, and conformally coupled fields into this model and study the pair production of charged particles. The semiclassical approach allows us to evaluate the induced current due to the pair production on the general dilatonic factor and electric field. Solving the field equations with the induced current, we find that the electric field shows a damped oscillation, whose amplitude decays to zero regardless of the values of the masses of charged fields. In other words, we derive a no-go theorem of anisotropic inflation by taking into account the Schwinger mechanism.