On Neutrino Masses and Mixings from Extra Dimensions

Abstract

In the framework of a Kaluza-Klein type theory with the Standard Model fields localized on a 4-dimensional section while gravity propagates in a full $4+\delta$-dimensional space-time, we examine a mechanism of naturally small neutrino mass generation through couplings of Standard Model singlet fermion(s) living also in the full space-time. A numerical studies is carried out on the charged current universality constraint from the ratio of pion decay partial widths. The bounds obtained on the fundamental mass scale could be stringent.

Comments: 16 pages latex, no figure; small modifications in discussions; version to appear in Phys.Lett. B