Predictive Model of Inverted Neutrino Mass Hierarchy and Resonant Leptogenesis

Abstract

We present a new realization of inverted neutrino mass hierarchy based on $S_3 \times {\cal U}(1)$ flavor symmetry. In this scenario, the deviation of the solar oscillation angle from $\pi/4$ is correlated with the value of $\theta_{13}$, as they are both induced by a common mixing angle in the charged lepton sector. We find several interesting predictions: $\te_{13}\geq 0.13$, $\sin^2\te_{12}\geq 0.31$, $\sin^2\te_{23}\simeq 0.5$ and $0\leq \cos \de \leq 0.7$ for the neutrino oscillation parameters and $0.01 {\rm eV}\stackrel{<}{_\sim}m_{\bt \bt}\stackrel{<}{_\sim} 0.02 {\rm eV}$ for the effective neutrino mass in neutrino-less double $\bt $-decay. We show that our scenario can also explain naturally the observed baryon asymmetry of the universe via resonant leptogenesis. The masses of the decaying right--handed neutrinos can be in the range $(10^3 - 10^7)$ GeV, which would avoid the generic gravitino problem of supersymmetric models.