From SIMP miracles to WIMP dead ends: navigating the freeze out of MeV-mass dark matter
J. Pradler* and
X. Chu*: corresponding author
Published on:
April 10, 2025
Abstract
We summarize here our studies [1–3] on two distinct scenarios for MeV-mass thermal dark matter freeze-out. First, we determine the minimal viable mass for dark matter below tens of MeV, considering annihilation into Standard Model particles, including photons, electrons, and neutrinos. Using a full three-sector abundance calculation, we track heat transfer between sectors and provide accurate thermal annihilation cross sections, particularly for velocity-dependent cases. The results identify fine-tuned regions where neutrino final states permit otherwise excluded p-wave annihilation scenarios. Second, we examine dark matter freeze-out in strongly interacting theories, where the relic abundance can be regulated not only through standard $3\pi \to 2\pi$ annihilation but also via bound-state formation~$X$, enabling effective two-body processes $XX \to \pi \pi$ and/or $\pi X \to \pi \pi$. Together, these studies highlight complementary pathways to thermal MeV-mass dark matter.
DOI: https://doi.org/10.22323/1.481.0086
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