Inflation from N-Forms and its stability

TL;DR

This paper explores inflation driven by n-forms, discovering new isotropic solutions, analyzing their stability, and establishing connections to f(R) gravity and scalar field models, with implications for anisotropic and isotropic inflation scenarios.

Contribution

It introduces new isotropic solutions for three-forms and analyzes the stability of n-form driven inflation, linking n-forms to f(R) gravity and scalar models.

Findings

New isotropic solutions for three-forms.

Two-forms are unstable during inflation due to nonminimal coupling.

Some n-form actions are equivalent to f(R) gravity and scalar field models.

Abstract

Anisotropic and isotropic slow-roll inflation supported by n-forms are sought. Canonical field strengths and their duals are taken into account, and they are allowed to have a potential and also, when necessary for slow-roll, a nonminimal curvature coupling. New isotropic solutions are found for three-forms. It is also shown that some n-form actions are equivalent to f(R) gravity and scalar field models with possible nonminimal couplings. Anisotropic solutions are found for two-forms, generalising vector inflation, however, also the two-form is unstable during inflation due to the nonminimal coupling to curvature. We also address the stability of the isotropic background solutions supported by a triad of vectors .