Large Lepton Mixing in a Coset-space Family Unification on $E_7/SU(5)\times U(1{)}^3$

Abstract

We study a coset-space unification model for families based on $E_7/SU(5)\times U(1{)}^3$. We find that qualitative structure of quark and lepton mass matrices in this model describes very well the observation. We stress, in particular, that the large mixing angle, ${\sin }^{2}2{\theta }_{{\nu }_{\mu }{\nu }_{\tau }}\simeq 1$, required for the atmospheric neutrino oscillation reported by the SuperKamiokande collaboration, is naturally obtained, which is a consequence of unparallel family structure in the present coset-space unification.

Comments: 8 pages, Latex2e