Constraining Axion and ALP Dark Matter from Misalignment during Reheating

TL;DR

This paper investigates how axion and ALP dark matter can be produced during inflationary reheating, expanding the viable parameter space and highlighting experimental constraints and future prospects.

Contribution

It introduces a novel analysis of axion/ALP production during reheating with generic inflaton potentials, extending the parameter space beyond standard models.

Findings

Reheating temperature affects relic abundance predictions.

Certain parameter regions are already constrained by existing experiments.

Future experiments will further restrict the viable parameter space.

Abstract

We explore the phenomenology of QCD axion and axion-like particle (ALP) dark matter production via misalignment during inflationary reheating. We investigate scenarios involving inflaton oscillating in a generic potential $\sim \phi^n$, considering inflaton decay and annihilation for reheating. For low reheating temperatures, the parameter space leading to the correct relic abundance can be enlarged beyond the standard case. Depending on the type of inflaton-matter couplings and the value of $n$, we find that certain parts of the extended parameter space are already constrained by ADMX, CAPP, and MUSE experiments. Future Haloscope experiments are expected to impose stringent constraints. We highlight the potential to utilize axion experiments in constraining the dynamics of reheating.