2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/50394We examine the structure of the Yukawa couplings in the 11 dimensional Horava-Witten M-theory based on non-standard embeddings. We find that the CKM and quark mass hierarchies can be explained in M Theory without introducing undue fine tuning. A phenomenological example is presented satisfying all CKM and quark mass data requiring the 5-branes cluster near the second orbifold plane, and that the instanton charges of the physical orbifold plane vanish. The latter condition is explicitly realized on a Calabi-Yau manifold with del Pezzo base dP_7.3 pages, latex, talk at DPF 2000, Columbus, OH, August 9-12, 2000High Energy Physics - TheoryHigh Energy Physics - Phenomenologytext