Stochastic axion scenario

By P. Graham, Adam Scherlis. Physical Review D, 2018

155 citations recorded by the source corpus.

For the minimal QCD axion model it is generally believed that overproduction of dark matter constrains the axion mass to be above a certain threshold, or at least that the initial misalignment angle must be tuned if the mass is below that threshold. We demonstrate that this is incorrect. During inflation, if the Hubble scale is low, the axion tends toward an equilibrium. This means the minimal QCD axion can naturally give the observed dark matter abundance in the entire lower part of the mass range, down to masses $\sim 10^{-12}$ eV (or $f_a$ up to almost the Planck scale). The axion abundance is generated by quantum fluctuations of the field during inflation. This mechanism generates cold dark matter with negligible isocurvature perturbations. In addition to the QCD axion, this mechanism can also generate a cosmological abundance of axion-like particles and other light fields.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/2e85990b19e857c7daa303133ee0c013bb9c799c

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Citations in the corpus

AION: an atom interferometer observatory and network (2019, background): “. These ultra-light bosons are also viable DM candidates, as they may well have acquired the observed abundance, e.g., through the misalignment mechanism [33{35] or quantum uctuations during in ation [36], and such DM bosons are naturally cold, as required by the standard cosmological paradigm for a”
The landscape of QCD axion models (2020, background): “without any fine tuning, in low-scale inflation models in which inflation lasts sufficiently long [275, 276].”
Physics potential of the International Axion Observatory (IAXO) (2019, background): “around and showed that the quantum fluctuations during a low-HI period of inflation may also be responsible for generating a large enough misalignment angle to give rise to QCD axion or ALP DM [108, 109].”