How light can ALP dark matter be?

[2511.15790] How light can ALP dark matter be? Skip to main content Search Submit Donate Log in High Energy Physics - Phenomenology arXiv:2511.15790 (hep-ph) [Submitted on 19 Nov 2025 ( v1 ), last revised 26 Aug 2026 (this version, v2)] Title: How light can ALP dark matter be? Authors: Kierthika Chathirathas , Thomas Schwetz View PDF HTML (experimental) Abstract: We assume axion-like particles (ALPs) to provide the full dark matter abundance and derive various lower bounds on the ALP mass. We contrast the post- and pre-inflationary symmetry breaking cases and present allowed regions in the plane of ALP mass and energy scale of inflation. For the post-inflationary case, we revisit bounds from isocurvature perturbations taking into account that, as suggested by simulations, axion radiation by cosmic strings during the scaling regime provides the dominant production mechanism of dark matter, obtaining significantly weaker limits than previously. Combining isocurvature, with constraints from black hole superradiance and free streaming, we find that the bound $m_a \gtrsim 10^{-17}$ eV applies for most cases considered here. It can be potentially relaxed to $\sim 6\times 10^{-19}$ eV only in the post-inflationary case with a strongly temperature-dependent axion mass, subject to uncertainties on the axion emission spectrum. Significantly stronger bounds are obtained in the post-inflationary scenario from the non-observation of CMB tensor modes, which can be as strong as $m_a > 5\times 10^{-7}$ eV for small reheating efficiencies, $\epsilon \lesssim 5\times 10^{-4}$. Comments: 37 pages, 12 figures. Version published in JCAP Subjects: High Energy Physics - Phenomenology (hep-ph) ; Cosmology and Nongalactic Astrophysics (astro-ph.CO) Cite as: arXiv:2511.15790 [hep-ph] (or arXiv:2511.15790v2 [hep-ph] for this version) https://doi.org/10.48550/arXiv.2511.15790 Focus to learn more arXiv-issued DOI via DataCite Journal reference: JCAP08(2026)041 Related DOI : https://doi.org/10.1088/1475-7516/2026/08/041 Focus to learn more DOI(s) linking to related resources Submission history From: Kierthika Chathirathas [ view email ] [v1] Wed, 19 Nov 2025 19:00:01 UTC (4,138 KB) [v2] Wed, 26 Aug 2026 21:01:15 UTC (4,549 KB) Full-text links: Access Paper: View PDF HTML (experimental) TeX Source view license Current browse context: hep-ph < prev | next > new | recent | 2025-11 Change to browse by: astro-ph astro-ph.CO References & Citations INSPIRE HEP SciX Google Scholar Semantic Scholar export BibTeX citation Bookmark Bibliographic Tools Bibliographic and Citation Tools Bibliographic Explorer Toggle Bibliographic Explorer ( What is the Explorer? ) Connected Papers Toggle Connected Papers ( What is Connected Papers? ) Litmaps Toggle Litmaps ( What is Litmaps? ) scite.ai Toggle scite Smart Citations ( What are Smart Citations? ) Code, Data, Media Code, Data and Media Associated with this Article alphaXiv Toggle alphaXiv ( What is alphaXiv? ) Links to Code Toggle CatalyzeX Code Finder for Papers ( What is CatalyzeX? ) DagsHub Toggle DagsHub ( What is DagsHub? ) GotitPub Toggle Gotit.pub ( What is GotitPub? ) Huggingface Toggle Hugging Face ( What is Huggingface? ) ScienceCast Toggle ScienceCast ( What is ScienceCast? ) Demos Demos Replicate Toggle Replicate ( What is Replicate? ) Spaces Toggle Hugging Face Spaces ( What is Spaces? ) Spaces Toggle TXYZ.AI ( What is TXYZ.AI? ) Related Papers Recommenders and Search Tools Link to Influence Flower Influence Flower ( What are Influence Flowers? ) Core recommender toggle CORE Recommender ( What is CORE? ) IArxiv recommender toggle IArxiv Recommender ( What is IArxiv? ) Author Venue Institution Topic About arXivLabs arXivLabs: experimental projects with community collaborators arXivLabs is a framework that allows collaborators to develop and share new arXiv features directly on our website. Both individuals and organizations that work with arXivLabs have embraced and accepted our values of openness, community, excellence, and user data privacy. arXiv is committed to these values and only works with partners that adhere to them. Have an idea for a project that will add value for arXiv's community? Learn more about arXivLabs . Which authors of this paper are endorsers? | Disable MathJax ( What is MathJax? ) We gratefully acknowledge support from our major funders , member institutions , and all contributors. About · Help · Contact · Subscribe · Copyright · Privacy · Accessibility · Operational Status (opens in new tab)

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