Speaker
Description
I point out a new effect on the freeze-out process of heavy particles induced by density perturbations in the early universe.
Already at moderately large density perturbations
I illustrate this effect with leptogenesis and discuss phenomenological implications.
I consider the simplest case of leptogenesis
and include only the decays and inverse decays of heavy neutrinos
in the presence of density perturbations.
As a result, I found that perturbations change
the freeze-out values of the lepton asymmetry,
and increase the spatial average of the asymmetry.
Furthermore, constraints on the mass of heavy neutrinos
become relaxed in the presence of perturbations
compared to the case without perturbations,
which is due to a beyond-linear effect caused by the
exponential decoupling of heavy neutrinos from the thermal bath.
