Fermion masses and mixings in supersymmetric SO(10) with third-generation quasi-Yukawa unification

A bstract We discuss the charged and neutral fermion masses and mixings in a supersymmetric SO(10) model with a minimal Higgs sector consisting of the multiplets 10 H , 45 H , and 16H+16̄ H . In addition to the renormalizable Yukawa couplings involving the Higgs 10-plet, we include non-renormalizable Yukawa couplings, which are important for reproducing with good accuracy the observed masses and mixings in the quark and lepton sectors. We identify a preferred solution which is compatible with third family quasi-Yukawa unification, namely y t ≈ y b ≈ 0 . 73 y τ at the unification scale, with the MSSM parameter tan β ~ 58. Acceptable solutions with lower tan β values are also realized in our framework, and we provide an example with tan β = 10. Based on our fits, the masses for the three right-handed neutrinos turn out to be ( M 1 , M 2 , M 3 ) ~ (10 9 , 8∙10 12 , 9∙10 12 ) GeV. We briefly discuss the metastable and quasistable string scenarios that can be realized in this class of supersymmetric SO(10) models.