Leptogenesis, mass hierarchies and low energy parameters

Leptogenesis in a left-right symmetric model is investigated for all possible neutrino mass hierarchies. The predictions of the model for low energy parameters as measured in neutrinoless double beta decay and in oscillation experiments are compared. The preferred values of the Majorana phases and limits on the smallest mass state are given. The main observation is that for the inverse hierarchy observable CP violation in oscillation experiments as well as a sizable signal in neutrinoless double beta decay can be expected. In a degenerate scheme, one Majorana phase is bounded to be around π/2 or π, and this ambiguity can easily be tested through neutrinoless double beta decay. The dependence of the baryon asymmetry on the different “Dirac” and “Majorana” phases is analyzed and a possibility to avoid the gravitino problem is discussed.