Rescuing Gravitational-Reheating in Chaotic Inflation

TL;DR

This paper demonstrates that a linear non-minimal coupling between the inflaton and gravity can enable successful inflation and reheating, with observable predictions for gravitational waves and implications for dark matter and matter-antimatter asymmetry.

Contribution

It introduces a gravity-assisted reheating mechanism in single-field inflation via a non-minimal coupling, consistent with observational bounds and testable by future experiments.

Findings

Non-minimal coupling range satisfies CMB and BBN constraints

Tensor-to-scalar ratio r ≥ 10^{-4} within experimental reach

Implications for dark matter and matter-antimatter asymmetry production

Abstract

We show, within the single-field inflationary paradigm, that a linear non-minimal interaction $\xi\,M_P\,\phi\,R$ between the inflaton field $\phi$ and the Ricci scalar $R$ can result in successful inflation that concludes with an efficient heating of the Universe via perturbative decays of the inflaton, aided entirely by gravity. Considering the inflaton field to oscillate in a quadratic potential, we find that $\mathcal{O}(10^{-1}) \lesssim \xi \lesssim \mathcal{O}(10^2)$ is required to satisfy the observational bounds from Cosmic Microwave Background (CMB) and Big Bang Nucleosynthesis (BBN). Interestingly, the upper bound on the non-minimal coupling guarantees a tensor-to-scalar ratio $r \gtrsim 10^{-4}$, within the range of current and future planned experiments. We also discuss implications of dark matter production, along with the potential generation of the matter-antimatter asymmetry resulting from inflaton decay, through the same gravity portal.