Resonant Reheating

TL;DR

This paper introduces a resonant reheating mechanism involving inflaton annihilation mediated by a massive scalar, revealing resonance effects that influence temperature evolution and have implications for dark matter production and gravitational wave detection.

Contribution

It uncovers resonance phenomena in inflaton reheating with monomial potentials and explores their effects on temperature dynamics, dark matter genesis, and gravitational wave signals.

Findings

Resonance occurs for inflaton potentials with n>2.

Temperature evolution during reheating shows non-trivial features.

Potential detection of resonant reheating signatures via gravitational waves.

Abstract

We investigate a novel reheating scenario proceeding through $s$-channel inflaton annihilation, mediated by a massive scalar. If the inflaton $\phi$ oscillates around the minimum of a monomial potential $\propto \phi^{n}$, we reveal the emergence of resonance phenomena originating from the dynamic evolution of the inflaton mass for $n>2$. Consequently, a resonance appears in both the radiation and the temperature evolution during the reheating process. By solving the coupled Boltzmann equations, we present solutions for radiation and temperature. We find non-trivial temperature characteristics during reheating, depending on the value of $n$ and the masses of the inflaton and mediator. Some phenomenological aspects of the model are explored. As a concrete example, we show that the same mediator participates in the genesis of dark matter, modifying the standard freeze-in dynamics. In addition, we demonstrate that the resonant reheating scenario could be tested by next-generation low- and high-frequency gravitational wave detectors.