CONSTRAINTS FROM UNIFICATION IN SU(5) AND SUSY SU(5)

We analyse the unification parameters M(GUT) and I/alpha(GUT) as funct ions of the numbers of fermion families (F) and Higgs doublets (H and H(SUSY)) within the standard model embedded in SU(5) and susy SU(5). A nalytical (where possible) and numerical solutions to first- and secon d-order approximations of the evolution equation for the couplings alp ha(i) are considered. As a result, restrictions on the unification par ameters constrain F, H and H(SUSY) in such a way that SU(5) is ruled o ut by constraints on H, and F is severely limited in susy SU(5).