A lower bound on dark matter mass

Abstract

We argue that there is a lower bound of order $10^{-19}$ eV on dark matter mass if it is produced after inflation via a process with finite correlation length. We rely on non-detection of free-streaming suppression and white-noise enhancement of density perturbations as the observational inputs.

Comments: v3: compared to v2, change in the definition of the suppression scale due to free streaming, 10^(-19) eV bound not affected, but stronger bounds in particular explicit examples weakened