Anisotropic power-law inflation for a model of two scalar and two vector fields

TL;DR

This paper introduces a multi-field inflation model with two scalar and two vector fields, demonstrating stable anisotropic power-law solutions under certain conditions, extending previous supergravity-inspired models.

Contribution

It presents a novel multi-field extension with non-minimal couplings, providing exact solutions and stability analysis for anisotropic inflation models.

Findings

Stable anisotropic power-law solutions for canonical scalar fields.

Instability of solutions when one scalar field is phantom.

Extension of supergravity-inspired models to multi-field scenarios.

Abstract

Inspired by an interesting counterexample to the cosmic no-hair conjecture found in a supergravity-motivated model recently, we propose a multi-field extension, in which two scalar fields are allowed to non-minimally couple to two vector fields, respectively. This model is shown to admit an exact Bianchi type I power-law solution. Furthermore, stability analysis based on the dynamical system method is performed to show that this anisotropic solution is indeed stable and attractive if both scalar fields are canonical. Nevertheless, if one of the two scalar fields is phantom then the corresponding anisotropic power-law inflation turns unstable as expected.