Phenomenological studies of rank-5 Calabi-Yau models

We study the phenomenology of heterotic superstring models compactified on Calabi-Yau manifolds with non-abelian fundamental groups which can yield the rank-5 gauge group SU(3)cxSU(2)LxU(1)2 in four dimensions. We examine one 2-generation model and several 4-generation models. They all have fatal problems with proton decay and/or neutrino masses. The most interesting 4-generation model avoids rapid proton decay at the expense of a neutrino weighing more than the proton and an unrealistic pattern of Cabibbo mixing. (orig.)