Implications of an additional scale on leptogenesis

Abstract

We consider variations of the standard leptogenesis picture arising from the presence of an additional scale related to the breaking of a $U(1)_X$ abelian flavor symmetry. We show that quite generically the presence of an additional energy scale might introduce new qualitative and quantitative changes on leptogenesis. Especially interesting is the possibility of having succesful TeV leptogenesis with a vanishing total CP violating asymmetry. By solving the corresponding Boltzmann equations it is shown that these kind of scenarios encounters no difficulties in generating the Cosmic baryon asymmetry.

9 pages, 8 figures. To appear in the proceedings of DISCRETE'08: Symposium on Prospects in the Physics of Discrete Symmetries, Valencia, Spain, 11-16 Dec 2008