Leptonic Custodial Symmetry, Quantization of the Electric Charge and the Neutrino in the Standard Model

Abstract

I study, in the leptonic sector, the role of the $SU(2)_V$ custodial symmetry \ti{\cal G} which was shown in ref. [1] to control the quantization of the electric charge in the $J=0$ mesonic sector. The electroweak theory is considered, according to ref. [2], as a purely vectorial model which interacts with a ``hidden'' sector of composite scalars. \ti{\cal G} can only be a symmetry of the former if the neutrino is a Majorana particle; the latter provides a dynamical modification of the leptonic weak couplings, reconstructing those of the Standard Model with a massless Majorana neutrino.Comment: 11 pages, Late