General Majorana Neutrino Mass Matrix from a Low Energy SU(3) Family Symmetry with Sterile Neutrinos

Abstract: Within the framework of a local SU(3) family symmetry model, we report a general analysis of the mechanism for neutrino mass generation and mixing, including light sterile neutrinos. In this scenario, ordinary heavy fermions, top and bottom quarks and tau lepton, become massive at tree level from Dirac See-saw mechanisms implemented by the introduction of a new set of $SU(2)L$ weak singlet vector-like fermions, U,D,E,N, with N a sterile neutrino. Right-handed and the $N{L,R}$ sterile neutrinos allow the implementation of a 8x8 general Majorana neutrino mass matrix with four or five massless neutrinos at tree level. Hence, light fermions, including light neutrinos get masses from radiative corrections mediated by the massive SU(3) gauge bosons. We report the corresponding Majorana neutrino mass matrix up to one loop. Previous numerical analysis of the free parameters show out solutions for quarks and charged lepton masses within a parameter space region where the vector-like fermion masses $M_U, M_D, M_E$, and the SU(3) family gauge boson masses lie in the low energy region of $\mathcal{O} (1-20)\,$TeV, with light neutrinos within the correct order of square neutrino mass differences: $m_2^2-m_1^2 \approx 7 \times 10^{-5}\;\text{eV}^2$, $m_3^2-m_1^2 \approx 2 \times 10^{-3}\;\text{eV}^2$, and at least one sterile neutrino of the order $\approx 0.5\;\text{eV}$. A more precise fit of the parameters is still needed to account also for the quark and lepton mixing.