Neutrino mass and mixing in the 3-3-1 model and S 3 flavor symmetry with minimal Higgs content

Abstract

A new S3 flavor model based on the SU(3)C ⊗ SU(3)L ⊗ U(1)X gauge symmetry responsible for fermion masses and mixings different from our previous work [14, 17] is constructed. The new feature is a two-dimensional representation of a Higgs anti-sextet under S3, which is responsible for neutrino masses and mixings. The neutrinos acquire small masses from only an anti-sextet of SU(3), which is in a doublet under S3. If the difference of components of the anti-sextet is regarded as a small perturbation, S3 is equivalently broken into identity, the corresponding neutrino mass mixing matrix acquires the most general form, and the model can fit the latest data on neutrino oscillations. This way of symmetry breaking helps us reduce a content in the Higgs sector, to only one anti-sextet instead of two as in our previous work [14]. Our results show that the neutrino masses are naturally small and a small deviation from the tri-bimaximal neutrino mixing form can be realized. The Higgs potential of the model as well as the minimization conditions and gauge boson masses and mixings are also considered.