Phenomenological Constraints on Axion Models of Dynamical Dark Matter

TL;DR

This paper analyzes phenomenological constraints on a bulk-axion dynamical dark matter model, highlighting its viability and implications for theories with many interacting and decaying particles, advancing the DDM framework.

Contribution

It provides a comprehensive phenomenological analysis of a specific axion-based DDM model, extending understanding of its constraints and broader implications.

Findings

The model satisfies key phenomenological constraints.

Implications for bulk axion theories are significant.

The framework can be applied to other multi-particle decay scenarios.

Abstract

In two recent papers (arXiv:1106.4546, arXiv:1107.0721), we introduced "dynamical dark matter" (DDM), a new framework for dark-matter physics in which the requirement of stability is replaced by a delicate balancing between lifetimes and cosmological abundances across a vast ensemble of individual dark-matter components whose collective behavior transcends that normally associated with traditional dark-matter candidates. We also presented an explicit model involving axions in large extra spacetime dimensions, and demonstrated that this model has all of the features necessary to constitute a viable realization of the general DDM framework. In this paper, we complete our study by performing a general analysis of all phenomenological constraints which are relevant to this bulk-axion DDM model. Although the analysis in this paper is primarily aimed at our specific DDM model, many of our findings have important implications for bulk axion theories in general. Our analysis can also serve as a prototype for phenomenological studies of theories in which there exist large numbers of interacting and decaying particles.