Speaker
Description
In the SO(10) GUTs with or without supersymmetry, the Yukawa couplings of the third-generation fermions can be unified by employing renormalization group (RG) analysis, similar to the gauge couplings. In the considered models, Yukawa unification implies that different Yukawa couplings are generated from a single coupling in the UV through the decomposition of scalar and fermion representations of the GUT group. Thus, the Yukawa hierarchy emerges from the CG coefficient of decomposition of the GUT group and vacuum expectation values (vevs) of different scalars. As earlier research has already examined the possibility of realizing Yukawa unification in the supersymmetric context, in this talk, we will focus on a non-supersymmetric SO(10) model with an intermediate Pati-Salam symmetry, where both gauge and Yukawa unification can be achieved simultaneously. As an explicit example, we will justify Yukawa unification in SO(10) originate from a single Yukawa coupling between fermion bidoublet ${\bf 27} \times {\bf 27}$ with a scalar multiplet ${\bf 351'}$ decomposed as ${\bf 10}+{\bf \overline{126}}+\dots $ in an $E_6$ model. Taking into account some phenomenological features such as the proton decay and the absence of flavor-changing neutral currents (FCNCs) at tree-level, we derive constraints on the parameters of the low energy model, in particular on the ratio of the two Higgs doublets vevs $\tan \beta$.
