Yukawa Textures And Horava-Witten M-Theory

The general structure of the matter Kahler metric in the ${\kappa }^{2\mathrm{/}3}$ expansion of Horava-Witten M-theory with nonstandard embeddings is examined. It is shown that phenomenological models based on this structure can lead to Yukawa and V${}_{\mathrm{C}\mathrm{K}\mathrm{M}}$ hierarchies (consistent with all data) without introducing ad hoc small parameters if the 5-branes lie near the distant orbifold plane and the instanton charges of the physical plane vanish. M-theory thus offers an alternate way of describing these hierarchies, different from the conventional models of Yukawa textures.