Yukawa Sector of Minimal SO(10) Unification

Abstract: We show that in SO(10) models, a Yukawa sector consisting of a real $10_H$, a real $120_H$ and a complex $126_H$ of Higgs fields can provide a realistic fit to all fermion masses and mixings, including the neutrino sector. Although the group theory of SO(10) demands that the $10_H$ and $120_H$ be real, most constructions complexify these fields and impose symmetries exterior to SO(10) to achieve predictivity. The proposed new framework with real $10_H$ and real $120_H$ relies only on SO(10) gauge symmetry, and yet has a limited number of Yukawa parameters. Our analysis shows that while there are restrictions on the observables, a good fit to the entire fermion spectrum can be realized. Unification of gauge couplings is achieved with an intermediate scale Pati-Salam gauge symmetry. Proton decay branching ratios are calculable, with the leading decay modes being $p \rightarrow \overline{\nu} \pi^+$ and $p \rightarrow e^+ \pi^0$.