No abstract

We prove that the values of the electroweak mixing angle sin 2 θ W and the intermediate mass scale M I have vanishing contributions due to one-loop, two-loop, and gravitational corrections in grand unified theories which accommodate an intermediate trinification symmetry (G 333D) invoked with spontaneous D-parity mechanism operative at mass scale greater than M I. The proof of the theorem is robust and we verify the results numerically using supersymmetric as well as nonsupersymmetric versions of E 6-GUT.