Speaker
Erdenebulgan Lkhagvadorj
(Sungkyunkwan University (KR))
Description
Light DM candidates, motivated by the absence of WIMP signals in direct detection experiments, can yield observable direct detection signals if they interact through light mediators with sizeable couplings. However, such interactions generally lead to an under-abundant relic density due to efficient annihilation into the light mediators. This tension can be naturally resolved if DM freezes out during a non-standard cosmological epoch, such as a stiff-fluid dominated era, which enhances the expansion rate. These modified thermal histories leave characteristic imprints on the stochastic GW background, providing a unique probe of pre-BBN dynamics through deviations in the high-frequency spectrum.