Bounds on minicharged neutrinos in the minimal standard model

Abstract

In the minimal standard model (MSM) with three generations of quarks and leptons, neutrinos can have tiny charges consistent with electromagnetic gauge invariance. There are three types of nonstandard electric charge given by Qst+ε(Li-Lj), where i,j=e,μ,τ (ij), Qst is the standard electric charge, Li is a family-lepton number, and ε is an arbitrary parameter which is put equal to zero in the usual incarnation of the MSM. These three nonstandard electric charges are of considerable theoretical interest because they are compatible with the MSM Lagrangian and SU(3)cSU(2)LU(1)Y gauge anomaly cancellation. The two most conspicuous implications of such nonstandard electric charges are the presence..