Speaker
Description
Weakly interacting massive particles (WIMPs) remain a well-motivated dark matter candidate. We study a minimal extension in which WIMPs are coupled to a heavier, feebly interacting partner that decays into them. In the early Universe, WIMPs in thermal equilibrium with the Standard Model serve as a portal to produce this heavy partner population. If the partner thermalizes and decays before WIMP freeze-out, the standard relic abundance is recovered. For weaker couplings, however, the partner decays after freeze-out and injects a non-thermal WIMP population, modifying the thermal history. This can lead to delayed freeze-out via re-annihilation or a subsequent freeze-in phase. In both regimes, achieving the observed relic abundance requires a larger WIMP annihilation cross section than in the standard scenario. As a result, current and upcoming indirect detection experiments can probe the partner’s mass and its coupling to WIMPs.