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arXiv · 1608.04092

Dark Matter in Axion Landscape

Ryuji Daido·Takeshi Kobayashi·Fuminobu Takahashi
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Abstract

If there are a plethora of axions in nature, they may have a complicated potential and create an axion landscape. We study a possibility that one of the axions is so light that it is cosmologically stable, explaining the observed dark matter density. In particular we focus on a case in which two (or more) shift-symmetry breaking terms conspire to make the axion sufficiently light at the potential minimum. In this case the axion has a flat-bottomed potential. In contrast to the case in which a single cosine term dominates the potential, the axion abundance as well as its isocurvature perturbations are significantly suppressed. This allows an axion with a rather large mass to serve as dark matter without fine-tuning of the initial misalignment, and further makes higher-scale inflation to be consistent with the scenario.

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Ryuji Daido, Takeshi Kobayashi, Fuminobu Takahashi. 2017-03-02. Dark Matter in Axion Landscape. https://doi.org/10.1016/j.physletb.2016.12.034

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