Angus Spalding

Three-Flavoured Thermal Leptogenesis Without Tuning

We investigate thermal leptogenesis in an extension of the Type-I seesaw in which a real singlet scalar couples non-diagonally to the right-handed neutrinos. The interactions $-y_{ij}\phi N_iN_j$, with $i\neq j$, introduce new sources of CP violation in heavy-neutrino decays with a negligible enhancement of the standar...