Intermediate mass scales in the nonsupersymmetricSO(10)grand unification: A reappraisal

Abstract

The constraints of gauge unification on intermediate mass scales in nonsupersymmetric $SO(10)$ scenarios are systematically discussed. With respect to the existing reference studies we include the $U(1)$ gauge mixing renormalization at the one- and two-loop level, and reassess the two-loop beta coefficients. We evaluate the effects of additional Higgs multiplets required at intermediate stages by a realistic mass spectrum and update the discussion to the present day data. On the basis of the obtained results, $SO(10)$ breaking patterns with up to two intermediate mass scales are discussed for potential relevance and model predictivity.