arXiv2002
In the context of the minimal supersymmetric seesaw model, we study the implications of the current neutrino data for thermal leptogenesis, $ββ_{0ν}$ decay, and leptonic flavour- and CP-violating low-energy observables. We express the heavy singlet-neutrino Dirac Yukawa couplings $(Y_ν)_{ij}$ and Majorana masses $M_{N_i}$ in terms of the light-neutrino observables and an auxiliary hermitian matrix $H$, which enables us to scan systematically over the allowed parameter space. If the lightest heavy neutrino $N_1$ decays induce the baryon asymmetry, there are correlations between the $M_{N_1}$, the lightest active neutrino mass and the primordial lepton asymmetry $ε_1$ on the one hand, and the $ββ_{0ν}$ decay parameter $m_{ee}$ on the other hand. {\it However, leptogenesis is insensitive to the neutrino oscillation phase}. We find lower bounds $M_{N_1}\gsim 10^{10}$ GeV for the normal light-neutrino mass hierarchy, and $M_{N_1}\gsim 10^{11}$ GeV for the inverted mass hierarchy, respectively, indicating a potentially serious conflict with the gravitino problem. Depending on $M_{N_1}$, we find upper (upper and lower bounds) on the lightest active neutrino mass for the normal (inverted) mass hierarchy, and a lower bound on $m_{ee}$ even for the normal mass ordering. The low-energy lepton-flavour- and CP-violating observables induced by renormalization are almost independent of leptogenesis. The electron electric dipole moment may be close to the present bound, reaching $d_e\sim 10^{-(27-28)}$ e cm in our numerical examples, while $d_μ$ may reach $d_μ\sim 10^{-25}$ e cm.