2023/11/02 by Nicolás Bernal, Bernal, Nicolás, Partha Konar +3 · 1 citation
Physics and Astronomy · #Advanced Thermodynamics and Statistical Mechanics #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph)
paper · doi:10.48550/arxiv.2311.01587
openalex publication_date 2023/11/02 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Model-independent theoretical upper bound on the thermal dark matter (DM) mass can be derived from the maximum inelastic DM cross-section featuring the whole observed DM abundance. We deploy partial-wave unitarity of the scattering matrix to derive the maximal thermally-averaged cross section for general number-changing processes r→ 2 (with r≥ 2), which may involve standard model particles or occur solely within the dark sector. The usual upper limit on the DM mass for s-wave annihilation is around 130 TeV (1 GeV) for r=2 (3), only applies in the case of a freeze-out occurring in the standard cosmological scenario. We consider the effects of two nonstandard cosmological evolutions, characterized by low-temperature reheating: i) a kination-like scenario and ii) an early matter-dominated scenario. In the first case, early freeze-out strengthens the unitarity bound to a few TeVs for WIMPs; while in the second case, the WIMP DM can be as heavy as ∼ 1010 GeV due to a large entropy dilution.