Schwinger effect in inflaton-driven electric field

Hiroyuki Kitamoto

doi:10.1103/physrevd.98.103512

Hiroyuki Kitamoto

Open Access

https://doi.org/10.1103/physrevd.98.103512

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Abstract

In a four dimensional inflation theory, a persistent electric field can be established by making the inflaton coupled to the gauge field like a dilaton. We investigate the pair production of scalar particles in the inflaton-driven electric field. In particular, we evaluate the induced current due to the pair production. The presence of the dilatonic coupling ensures the validity of the WKB approximation at the past and the future infinities, without tuning constant parameters. Thus, the semiclassical description is applicable in evaluating the induced current. Solving the field equations with the induced current, we evaluate the first-order backreaction to the electric field. It turns out that the electric field decreases with the cosmic expansion. The result indicates that the no-anisotropic hair theorem for inflation holds true regardless of whether the dilatonic coupling is present or not.

Highlights

Concerning the primordial universe, we find no evidence of statistical anisotropy from the current status of cosmic microwave background observations [1,2]
II, we review the classical solution in the inflation theory with the dilatonic coupling
Where we kept the lowest order in εV, i.e., we treated the btiaocnkagl rtooupndffiεffiffiVffiffis.pIatcsehtoimuled as be de Sitter (dS) space except that E is propornoted that if the dilatonic coupling is absent as f 1⁄4 1, we cannot obtain a persistent electric field as a classical solution

Summary

INTRODUCTION

Concerning the primordial universe, we find no evidence of statistical anisotropy from the current status of cosmic microwave background observations [1,2]. Watanabe, and Soda showed that a persistent electric field can be obtained by introducing a dilatonic coupling between the inflaton and the gauge field in the action [3]. It is reasonable to conjecture that if we take into account the Schwinger effect in the inflaton-driven electric field, the no-anisotropic hair theorem holds true in the presence of the dilatonic coupling. We point out that the presence of the dilatonic coupling ensures the validity of the Wentzel-Kramers-Brillouin (WKB) approximation at the past and the future infinities, without tuning constant parameters. Based on this fact, we evaluate the induced current by using the semiclassical description.

BACKGROUND

TEST SCALAR FIELD

INDUCED CURRENT DUE TO PAIR PRODUCTION

BACKREACTION FROM INDUCED CURRENT

Findings

CONCLUSION