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

Abstract

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 $16_H + \overline{16}_H$. 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 $y_t \approx y_b \approx 0.73 y_{\tau}$ at the unification scale, with the MSSM parameter $\tan\beta \sim 58$. Acceptable solutions with lower $\tan\beta$ values are also realized in our framework, and we provide an example with $\tan \beta =10$. Based on our fits, the masses for the three right-handed neutrinos turn out to be $\left(M_1,M_2,M_3\right)\sim \left(10^9, 8\cdot 10^{12}, 9\cdot 10^{12}\right) \mathrm{GeV}$. We briefly discuss the metastable and quasistable string scenarios that can be realized in this class of supersymmetric SO(10) models.