Resonant Primordial Gravitational Waves Amplification

TL;DR

This paper introduces a model of inflation with a massive graviton that resonantly amplifies primordial gravitational waves, potentially bypassing the Lyth bound and aligning with observational constraints.

Contribution

It proposes a minimal extension of single-field inflation with a transient graviton mass causing resonant tensor amplification, a novel mechanism in early universe cosmology.

Findings

Resonant amplification of tensor modes during reheating.

Graviton mass oscillates coherently, enhancing gravitational waves.

Model recovers standard GR after reheating.

Abstract

We propose a mechanism to evade the Lyth bound in models of inflation. We minimally extend the conventional single-field inflation model in general relativity (GR) to a theory with non-vanishing graviton mass in the very early universe. The modification primarily affects the tensor perturbation, while the scalar and vector perturbations are the same as the ones in GR with a single scalar field at least at the level of linear perturbation theory. During the reheating stage, the graviton mass oscillates coherently and leads to resonant amplification of the primordial tensor perturbation. After reheating the graviton mass vanishes and we recover GR.