In the context of the minimal supersymmetric seesaw model, we study the implications of the current neutrino data for thermal leptogenesis, $\beta\beta_{ 0\nu}$ decay, and leptonic flavour- and CP-violating low-energy observables. We express the heavy singlet-neutrino Dirac Yukawa couplings $(Y_\nu)_{ ij}$ 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 $\epsilon_1$ on the one hand, and the $\beta\beta_{ 0\nu}$ 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 $d_\mu$ may reach $d_\mu\sim 10^{ -25}$ e cm.
Categories: hep-ph