Three fermionic generations on a topological defect in extra dimensions

Abstract

We suggest a mechanism explaining the origin of three generations of the Standard Model fermions from one generation in a higher-dimensional theory. Four-dimensional fermions appear as zero modes trapped in the core of a topological defect with topological number three. We discuss hierarchical pattern of masses and mixings which arises in these models.

Comments: 19 pages, no figures; v.2: references added, main text unchanged