On the validity of cosmic no-hair conjecture in an anisotropic inflationary model

TL;DR

This paper investigates the cosmic no-hair conjecture within an anisotropic inflationary model, revealing its potential violation due to scalar-electromagnetic coupling but also conditions under which it can be restored with phantom fields.

Contribution

It demonstrates the conditions under which the cosmic no-hair conjecture is violated or upheld in the Kanno-Soda-Watanabe anisotropic inflation model, considering different scalar field types.

Findings

The conjecture is generally violated with standard scalar fields.

Introduction of phantom fields restores the conjecture.

Coupling between scalar and electromagnetic fields influences validity.

Abstract

We will present main results of our recent investigations on the validity of cosmic no-hair conjecture proposed by Hawking and his colleagues long time ago in the framework of an anisotropic inflationary model proposed by Kanno, Soda, and Watanabe. As a result, we will show that the cosmic no-hair conjecture seems to be generally violated in the Kanno-Soda-Watanabe model for both canonical and non-canonical scalar fields due to the existence of a non-trivial coupling term between scalar and electromagnetic fields. However, we will also show that the validity of the cosmic no-hair conjecture will be ensured once a unusual scalar field called the phantom field, whose kinetic energy term is negative definite, is introduced into the Kanno-Soda-Watanabe model.