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arXiv · 1708.06047

Adiabatic suppression of the axion abundance and isocurvature due to coupling to hidden monopoles

Masahiro Kawasaki·Fuminobu Takahashi·Masaki Yamada
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Abstract

The string theory predicts many light fields called moduli and axions, which cause a cosmological problem due to the overproduction of their coherent oscillation after inflation. One of the prominent solutions is an adiabatic suppression mechanism, which, however, is non-trivial to achieve in the case of axions because it necessitates a large effective mass term which decreases as a function of time. The purpose of this paper is twofold. First, we provide an analytic method to calculate the cosmological abundance of coherent oscillation in a general situation under the adiabatic suppression mechanism. Secondly, we apply our method to some concrete examples, including the one where a string axion acquires a large effective mass due to the Witten effect in the presence of hidden monopoles.

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Masahiro Kawasaki, Fuminobu Takahashi, Masaki Yamada. 2017-08-21. Adiabatic suppression of the axion abundance and isocurvature due to coupling to hidden monopoles. https://doi.org/10.1007/jhep01(2018)053

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