CONSTRUCTION OF GRAND UNIFIED MODELS BY DIMENSIONAL REDUCTION

We discuss the problem of building grand unified models in the framework of the dimensional reduction method. In particular, we derive the bosonic sector of the flipped SU(5) grand unified model leading to correct spontaneous symmetry breaking and admitting the hierarchy of masses. For that purpose, we develop a new technique for constructing bases of generators adapted to reductions of representations of Lie algebras to subalgebras.