Pre-heating in the framework of massive gravity

TL;DR

This paper introduces a natural preheating mechanism in the early universe via inflaton-dependent mass terms for gravitational waves within a massive gravity framework, enabling universe reheating without extra matter couplings.

Contribution

It proposes a novel preheating process driven by resonant amplification of gravitational waves due to inflaton-dependent mass in massive gravity theories.

Findings

Resonant amplification of gravitational waves occurs during inflaton oscillations.

Preheating can be achieved without arbitrary matter-inflaton couplings.

The mechanism naturally transitions the universe into the reheating phase.

Abstract

In this paper we propose a mechanism of natural preheating of our universe by introducing an inflaton field dependent mass term for the gravitational wave for a specific class of massive gravity theory. For any single field inflationary model, the inflaton must go through the oscillatory phase after the end of inflation. As has recently been pointed out, if the gravitational fluctuation has inflaton dependent mass term, there will be a resonant amplification of the amplitude of the gravitational wave during the oscillatory phase of inflaton. Because of this large enhancement of the amplitude of the gravitational wave due to parametric resonance, we show that universe can naturally go through the pre-reheated phase with minimally coupled matter field. Therefore, during the reheating phase, there is no need to introduce any arbitrary coupling between the matter field and the inflaton .