Axion as a non-WIMP dark matter candidate

TL;DR

This paper reviews the theoretical basis and recent developments in axion dark matter, emphasizing their non-thermal production mechanisms and the resulting mass range predictions across different cosmological models.

Contribution

It provides a comprehensive overview of axion as a dark matter candidate, highlighting recent advances in relic abundance estimation and production mechanisms.

Findings

Axions can account for dark matter in various mass ranges.

Non-thermal production mechanisms are crucial for axion relic abundance.

Different cosmological scenarios predict distinct axion mass ranges.

Abstract

The axion arises in well-motivated extensions of the Standard Model of particle physics and is regarded as an alternative to the weakly interacting massive particle paradigm to explain the nature of dark matter. In this contribution, we review theoretical aspects of dark matter axions, particularly focusing on recent developments in the estimation of their relic abundance. A closer look at their non-thermal production mechanisms in the early universe reveals the possibility of explaining the observed dark matter abundance in various mass ranges. The mass ranges predicted in various cosmological scenarios are briefly summarized.