Gravitational waves from inflation with antisymmetric tensor field

TL;DR

This paper investigates inflation driven by a rank-2 antisymmetric tensor field, analyzing background dynamics, gravitational wave propagation, and stability, with implications for the tensor power spectrum and spectral index.

Contribution

It provides a comprehensive analysis of inflation with an antisymmetric tensor field, including tensor perturbations, stability conditions, and gravitational wave evolution, extending previous studies.

Findings

Model satisfies gravitational wave speed constraints

Tensor perturbations are free from ghost instabilities

Calculated tensor power spectrum and spectral index

Abstract

We build upon the past studies of inflation with rank-2 antisymmetric tensor field, including here the tensor perturbations to metric. We perform a comprehensive analysis of the background dynamics of our model in the presence of non-minimal coupling curvature terms $R$ and $R_{\mu \nu}$. We find appropriate conditions on the nonminimal coupling parameters to satisfy the constraint of speed of propagation of gravitational waves. Including the tensor perturbations, the model is found to be free from ghost instabilities with minimal constraints on the parameters. We also study the evolution of gravitational waves, calculate the power spectrum and the tensor spectral index.