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

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.