Speaker
Description
We consider Dark Matter (DM) production via the freeze-in mechanism with finite temperature corrections. Freeze-in is mostly sensitive to temperatures corresponding to the highest energy scale involved in the production reactions, contrary to the freeze-out paradigm, which occurs well within a non-relativistic regime. As a result, quantum and finite temperature corrections can significantly alter the predictions for the DM production rate and hence for its relic abundance. However, the conventional Boltzmann approach widely employed in the freeze-in literature is not suited to capture the relevant effects that contribute to the evolution of particle number densities throughout all temperature regimes; for instance, the use of thermal masses to regulate infrared divergences in scattering amplitude comes as an artificial ad-hoc expedient.
Here, I discuss some recent advancements of an ongoing effort to consistently calculate the DM production rate from first principles, combining the real-time approach of thermal quantum field theory with Schwinger–Dyson equations derived from a two-particle irreducible (2PI) effective action. We compare our results with the Boltzmann approach, both in vacuum and with using thermal masses. Moreover, we discuss the applicability and accuracy of these various approaches for phenomenological studies.
