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arXiv · 2510.22974

Bose-Einstein Condensate Cosmology within the Framework of QCD Axion

Takeshi Fukuyama
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Abstract

Bose-Einstein Condensation (BEC) cosmology is analyzed in the framework of a string-inspired axion model. The dispersion relation of the axionic mode includes both gravitational and self-interaction terms, the latter being small in magnitude but crucial for inducing instability of the condensate. The generation rate of BEC around redshift $z\approx 30$ is primarily governed by gravity, consistent with a phenomenological value $\Gamma\approx 10^{-31}$ eV adopted in previous work and realizable for the QCD axion. The relation between this early BEC epoch and the later formation of supermassive black holes at $z\approx 5$ is also discussed.

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Takeshi Fukuyama. 2025-10-27. Bose-Einstein Condensate Cosmology within the Framework of QCD Axion. https://arxiv.org/abs/2510.22974

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