SU(16) grand unification: Breaking scales, proton decay, and neutrino magnetic moment

We give a detailed renormalization group analysis for the SU(16) grand unified group with general breaking chains in which quarks and leptons transform separately at intermediate energies. Our analysis includes the effects of Higgs bosons. We show that the grand unification scale could be as low as ∼${10}^{8.5}$ GeV and give examples where new physics could exist at relatively low energy (∼250 GeV). We consider proton decay in this model and show that it is consistent with a low grand unification scale. We also discuss the possible generation of a neutrino magnetic moment in the range of ${10}^{\mathrm{-}11}$ to ${10}^{\mathrm{-}10}$ ${\mathrm{\mu }}_{\mathit{B}}$ with a very small mass by the breaking of the embedded SU(2${)}_{\nu }$ symmetry at a low energy.