In this paper we show how some flavor symmetries may be derived from the heterotic string, when compactified on a 6D orbifold. In the body of the paper we focus on the D4 family symmetry, recently obtained in Z3×Z2 orbifold constructions. We show how this flavor symmetry constrains fermion masses, as well as the soft SUSY breaking mass terms. Flavor symmetry breaking can generate the hierarchy of fermion masses and at the same time the flavor symmetry suppresses large flavor changing neutral current processes.
@article{arxiv.0704.2807,
title = {String-derived D4 flavor symmetry and phenomenological implications},
author = {Pyungwon Ko and Tatsuo Kobayashi and Jae-hyeon Park and Stuart Raby},
journal= {arXiv preprint arXiv:0704.2807},
year = {2014}
}