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WS26/27 – Abstract
James Unwin
(University of Illinois Chicago)
22.10.2026
Freeze-in Dark Matter
The traditional WIMP scenario suggests that dark matter was once in thermal equilibrium with the Standard Model thermal bath before undergoing pair annihilation and subsequent `freeze-out'. The residual WIMPs that survive freeze-out then constitute the relic abundance of dark matter today. Freeze-in dark matter considers the opposite possibility; interactions in the thermal bath lead to dark matter production, but it never reaches thermal equilibrium. In this talk, I will first outline the two distinct realisations of this class of models, referred to as IR freeze-in and UV freeze-in. Subsequently, I will highlight the interesting possibility that the dark matter mass could exceed the highest temperatures ever reached by the thermal bath in the early universe, leading to a Boltzmann-suppressed production cross section. Building on this scenario, I will outline a highly minimal model of freeze-in dark matter in which dark matter freeze-in occurs via the electroweak gauge bosons. I will highlight the observational constraints on this model and the opportunities for discovering such a scenario at next-generation experiments.
