2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/194504We introduce a flavor ${\cal U}(1)$ symmetry à la Froggat-Nielsen to explain the magnitude of the CKM mixing angles as well bilarge mixing in the neutrino sector. In the framework of GUTs we also estimate the magnitude of the third leptonic mixing angle $θ_{13}$. Estimates for rare leptonic decays such as $μ\to e \ga $ are also provided. Finally, leptogenesis is exploited for estimating the magnitude of leptonic CP violation.Corrected typos and some numerics in calculation of leptogenesis, references added. To be published in Nucl. Phys. BHigh Energy Physics - Phenomenologytext