Leptogenesis and low energy observables

Leptogenesis can link the smallness of neutrino masses as implied by neutrino oscillations with the non–vanishing baryon asymmetry of the universe. This connection is provided by the see–saw mechanism. It is interesting to ask if one can relate also the CP violation required for leptogenesis at high energy with the CP violation at low energy as measurable in neutrino oscillation experiments or neutrinoless double beta decay. Though in general this is not possible, various approaches can very well link these phenomena. An Ansatz with minimal input — namely a hierarchical Dirac mass matrix — is presented and its consequences for leptogenesis, neutrino mixing and neutrinoless double beta decay are analyzed. PACS: 14.60.St 12.60.-i 13.35.Hb 14.60.P