2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/198481Sufficient conditions for the relation $tan β\simeq m_t/m_b$ to hold in supersymmetric grand unified theories are formulated. Essential ingredients are the $SU(2)_R$ gauge symmetry and a discrete matter parity. The applicability of our conditions is illustrated by specific examples. Implications for neutrino masses are discussed.13 pages, LaTeX, UT-STPD-1-94High Energy Physics - Phenomenologytext