Vanishing corrections on intermediate scale and implications for unification of forces

摘要

In two-step breakings of a class of grand unified theories including SO(10), we prove a theorem showing that the scale (M(sub I)) where the Pati-Salam gauge symmetry with parity breaks down to the standard gauge group, has vanishing corrections due to all sources emerging from higher scales ((mu) > M(sub I)) such as the one-loop and all higher-loop effects, the GUT-threshold, gravitational smearing, and string threshold effects. Implications of such a scale for the unification of gauge couplings with small Majorana neutrino masses are discussed. In string inspired SO(10), we show that M(sub I) (approx equal) 5 x 10(sup 12) GeV, needed for neutrino masses, with the GUT scale M(sub U) (approx equal) M(sub str) can be realized provided certain particle states in the predicted spectrum are light. (author). 28 refs, 1 tab. (Atomindex citation 27:066735)