Heavy QCD axion dark matter from avoided level crossing

Jun 7, 2023
6 pages
Published in:
  • Phys.Rev.D 108 (2023) 9, L091703
  • Published: Nov 1, 2023
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Abstract: (APS)
The QCD axion offers a natural resolution to the strong-CP problem and provides a compelling dark matter candidate. If the QCD axion constitutes all the dark matter, the simplest models pick out a narrow range of masses around 100μeV. We point out a natural production mechanism for QCD axion dark matter at masses up to existing astrophysical bounds [O(20meV) for the most minimal models and O(1eV) for nucleophobic models]. If the QCD axion mixes with a sterile axion, the relative temperature dependence of their potentials can lead to an avoided level crossing of their mass eigenstates. This leads to a near-total transfer of energy density from the sterile axion to the QCD axion, resulting in a late-time QCD axion abundance sufficient to make up all of present-day dark matter. Our result provides additional theoretical motivation for several direct detection experiments that will probe this part of parameter space in the near future.
Note:
  • 6 pages, 2 figures, matches published version
  • quantum chromodynamics: axion
  • axion: dark matter
  • strong interaction: CP
  • up: mass
  • energy: density
  • crossing
  • axion: mass
  • numerical calculations
  • sterile
  • resolution