Fermion masses in supersymmetric SO(10) with type II seesaw mechanism: A nonminimal predictive scenario

A predictive framework for fermion masses and mixing is given by the supersymmetric SO(10) model with one 10(H), one (1) over bar 26(H), one 126(H), and one 210(H) Higgs representations, and type-II seesaw dominating the neutrino mass matrix. We investigate the origin of the tension between this model and lepton mixing data and refine previous numerical analyses. We discuss an extension of the minimal model that includes one 120(H) chiral superfield representation. This exhausts the possible renormalizable contributions to the Yukawa sector. In spite of the increase in the number of parameters the predictivity of the minimal setting is not spoiled. We argue that the contributions to fermion masses due to the doublet components of 120(H) can be naturally small compared to those of 10(H) and (126) over bar (H), thus acting as a perturbation in the fermion mass generation. The antisymmetric nature of the 120(H) Yukawa coupling affects at leading order the determination of the mixing angles and it allows to remove the inconsistencies between predictions and data on the neutrino parameters. An improvement in the experimental bound on U-e3 can tell this scenario from the minimal model.