In the coming decades, the search for particle physics with cosmological probes is expected to become an increasingly active field.
In this talk, I focus on supersymmetric models in which the gravitino mass is in the 100eV~1keV range, and point out that these models have a characteristic feature in the inflationary gravitational waves in the 10−10−10−5Hz band: In such models, gravitino exists as a warm component of dark matter. However, the amount of such warm components is stringently constrained from cosmological small scale structures, in particular the number count of satellite galaxies. This requires entropy production in the early Universe, which must occur after the gravitino decoupling from the SM thermal bath. As a result, a characteristic structure is imprinted in the inflationary gravitational wave spectrum in a specific frequency band.
In this talk, I first give an overview of how particle models can leave their imprint on the gravitational wave spectrum in general, and then explain the case with supersymmetric models mentioned above. This talk is based on 2107.12804 with Gongjun Choi and Tsutomu T. Yanagida.