Primordial Tensor Non-Gaussianity from Massive Gravity

TL;DR

This paper investigates the tensor bispectrum in a massive gravity theory, revealing a potentially observable squeezed bispectrum with unique features influenced by graviton mass, differing from general relativity predictions.

Contribution

It introduces a new 3-point interaction in massive gravity that enhances the tensor bispectrum, especially in the squeezed configuration, offering novel observational signatures.

Findings

Tensor bispectrum is larger than in general relativity.

The bispectrum peaks at the squeezed configuration.

The slope of the bispectrum depends on graviton mass.

Abstract

We calculate tensor bispectrum in a theory of massive tensor gravitons which predicts blue-tilted and largely amplified primordial gravitational waves. We find that a new 3-point interaction can produce a larger tensor bispectrum than the conventional one from general relativity. The bispectrum peaks at the squeezed configuration and its slope towards the squeezed limit is determined by the graviton mass. This squeezed tensor bispectrum may be observed as the quadrupolar modulation of the tensor power spectrum by interferometers.