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arXiv · 2101.10330

Breakdown of chiral perturbation theory for the axion hot dark matter bound

Luca Di Luzio·Guido Martinelli·Gioacchino Piazza
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Abstract

We show that the commonly adopted hot dark matter (HDM) bound on the axion mass $m_a \lesssim$ 1 eV is not reliable, since it is obtained by extrapolating the chiral expansion in a region where the effective field theory breaks down. This is explicitly shown via the calculation of the axion-pion thermalization rate at the next-to-leading order in chiral perturbation theory. We finally advocate a strategy for a sound extraction of the axion HDM bound via lattice QCD techniques.

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Luca Di Luzio, Guido Martinelli, Gioacchino Piazza. 2021-01-25. Breakdown of chiral perturbation theory for the axion hot dark matter bound. https://doi.org/10.1103/physrevlett.126.241801

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