Inflation with an antisymmetric tensor field

TL;DR

This paper explores inflation driven by an antisymmetric tensor field, showing that nonminimal gravitational couplings enable stable de-Sitter solutions with sub-Planckian parameters, and analyzing the stability of perturbations.

Contribution

It demonstrates that nonminimal couplings of antisymmetric tensor fields can produce stable inflationary solutions, which was not possible with minimal coupling models.

Findings

Minimal models do not support inflation.

Nonminimal couplings lead to stable de-Sitter solutions.

Sub-horizon modes are free of ghost instability.

Abstract

We investigate the possibility of inflation with models of antisymmetric tensor field having minimal and nonminimal couplings to gravity. Although the minimal model does not support inflation, the nonminimal models, through the introduction of a nonminimal coupling to gravity, can give rise to stable de-Sitter solutions with a bound on the coupling parameters. The values of field and coupling parameters are sub-planckian. Slow roll analysis is performed and slow-roll parameters are defined which can give the required number of e-folds for sufficient inflation. Stability analysis has been performed for perturbations to antisymmetric field while keeping the metric unperturbed, and it is found that only the sub-horizon modes are free of ghost instability for de-Sitter space.