Some Properties of Multi-Component Axion Dark Matter

Fuente: arXiv
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Autor principal: Li, Hai-Jun
Formato: Preprint
Publicado: 2025
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author Li, Hai-Jun
author_facet Li, Hai-Jun
contents We introduce a mechanism for multi-component dark matter (DM) that originates from axion mixing and present some of its defining properties. In this context, multi-component DM implies that the cold DM is composed of the QCD axion and many ultra-light axion-like particles (ALPs). This framework can be realized in the type IIB string axiverse with hierarchical axion masses and decay constants. Our investigation reveals that in the light QCD axion scenario, the energy density of the lightest ALP often dominates after mixing. On the other hand, in the heavy QCD axion scenario, both the QCD axion and non-lightest ALPs may dominate, depending on the ALP decay constants. Under certain conditions, the QCD axion can dominate the DM budget. Finally, we briefly discuss a theoretical framework featuring $\sim\mathcal{O}(100)$ axions, with hierarchical axion masses and decay constants.
format Preprint
id arxiv_https___arxiv_org_abs_2510_22569
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Some Properties of Multi-Component Axion Dark Matter
Li, Hai-Jun
High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
We introduce a mechanism for multi-component dark matter (DM) that originates from axion mixing and present some of its defining properties. In this context, multi-component DM implies that the cold DM is composed of the QCD axion and many ultra-light axion-like particles (ALPs). This framework can be realized in the type IIB string axiverse with hierarchical axion masses and decay constants. Our investigation reveals that in the light QCD axion scenario, the energy density of the lightest ALP often dominates after mixing. On the other hand, in the heavy QCD axion scenario, both the QCD axion and non-lightest ALPs may dominate, depending on the ALP decay constants. Under certain conditions, the QCD axion can dominate the DM budget. Finally, we briefly discuss a theoretical framework featuring $\sim\mathcal{O}(100)$ axions, with hierarchical axion masses and decay constants.
title Some Properties of Multi-Component Axion Dark Matter
topic High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
url https://arxiv.org/abs/2510.22569