Non-thermal production of Dark Matter after Inflation

TL;DR

This paper investigates non-thermal dark matter production after inflation, focusing on scalar dark matter and inflaton interactions, highlighting how self-interactions influence relic abundance during preheating.

Contribution

It introduces a simple extension of the Standard Model with an inflaton and scalar dark matter, analyzing non-thermal production during preheating and the effects of self-interactions.

Findings

Dark matter can be overproduced in certain parameter regions.

Large self-interactions can suppress dark matter abundance.

Self-interactions help achieve observed relic abundance through cannibalization.

Abstract

The existence of Dark Matter (DM) has been well established from various cosmological and astrophysical evidences. However, the particle properties of DM are largely undetermined and attempts to probe its interactions with the Standard Model (SM) particles have, so far, not met with any success. The stringent constraints on the DM-SM interactions, while does not exclude the standard lore of producing weakly massive interacting particle DM candidates through thermal freeze-out mechanism in its entirety, have certainly cast shadow on the same. In this work, we consider non-thermal production of DM within a simple extension of the SM including an inflaton field and a scalar DM candidate. Assuming negligible interactions between the SM particles and the DM, we study the production of the latter at the end of inflation, during the (p)reheating epoch. In this context, we explore the role of DM self-interactions and its interaction with the inflaton field, and find that DM can be over produced in a significant region of the parameter space. We further demonstrate that large self-interaction of the DM can suppress its abundance during preheating and to a certain extent helps to achieve the observed relic abundance via cannibalization.