Leptogenesis describes the dynamical generation of the matter antimatter asymmetry in our universe by invoking right-handed neutrinos. Here, I will present a leptogenesis mechanism based on the standard type-I seesaw model that, contrary to the standard lore, successfully operates with right-handed neutrinos which have relatively low masses, large couplings and negligible CP violation. The key idea behind wash-in leptogenesis is to generalize standard freeze-out leptogenesis to a nonminimal cosmological background in which the chemical potentials of all particles not in chemical equilibrium at the temperature of leptogenesis are allowed to take arbitrary values. This sets the stage for constructing new baryogenesis models where chemical potentials generated at high temperatures are reprocessed to generate a nonvanishing B-L asymmetry at low temperatures. As concrete examples, I discuss wash-in leptogenesis after axion inflation and in the context of grand unification.
Friday, March 5, 2021 - 12:45