Cosmological implications of axion-matter couplings

Green, Daniel; Guo, Yi; Wallisch, Benjamin

doi:10.1088/1475-7516/2022/02/019

Title: Cosmological implications of axion-matter couplings

Journal Article · 09 February 2022 · Journal of Cosmology and Astroparticle Physics

DOI: https://doi.org/10.1088/1475-7516/2022/02/019 · OSTI ID:1979354

Green, Daniel ^[1]; Guo, Yi ^[2]; Wallisch, Benjamin ^[3]

University of California San Diego, La Jolla, CA (United States); Univ. of California, San Diego, CA (United States)
University of California San Diego, La Jolla, CA (United States)
University of California San Diego, La Jolla, CA (United States); Institute for Advanced Study, Princeton, NJ (United States)

Axions and other light particles appear ubiquitously in physics beyond the Standard Model, with a variety of possible couplings to ordinary matter. Cosmology offers a unique probe of these particles as they can thermalize in the hot environment of the early universe for any such coupling. For sub-MeV particles, their entropy must leave a measurable cosmological signal, usually via the effective number of relativistic particles, N_eff. Here, in this paper, we will revisit the cosmological constraints on the couplings of axions and other pseudo-Nambu-Goldstone bosons to Standard Model fermions from thermalization below the electroweak scale, where these couplings are marginal and give contributions to the radiation density of ΔN_eff > 0.027. We update the calculation of the production rates to eliminate unnecessary approximations and find that the cosmological bounds on these interactions are complementary to astrophysical constraints, e.g. from supernova SN 1987A. We additionally provide quantitative explanations for these bounds and their relationship.

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Research Organization:: University of California San Diego, La Jolla, CA (United States)

Sponsoring Organization:: USDOE Office of Science (SC); Simons Foundation; National Science Foundation (NSF)

Grant/Contract Number:: SC0009919; SC0019035

OSTI ID:: 1979354

Journal Information:: Journal of Cosmology and Astroparticle Physics, Journal Name: Journal of Cosmology and Astroparticle Physics Journal Issue: 02 Vol. 2022; ISSN 1475-7516

Publisher:: Institute of Physics (IOP)Copyright Statement

Country of Publication:: United States

Language:: English

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79 ASTRONOMY AND ASTROPHYSICS
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cosmology of theories beyond the SM
particle physics
physics of the early universe

Title: Cosmological implications of axion-matter couplings

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