Neutrino masses and mixing within a SU(3) family symmetry model with one or two light sterile neutrinos

Abstract

We report a global fit of parameters for fermion masses and mixing, including light sterile neutrinos, within a local vector $SU(3)$ family symmetry model. In this scenario, ordinary heavy fermions, top and bottom quarks and tau lepton, become massive at tree level from {\bf 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. The $N_{L,R}$ sterile neutrinos allow the implementation of a $8\times 8$ general tree level See-saw Majorana neutrino mass matrix with four massless eigenvalues. Hence, light fermions, including light neutrinos obtain masses from one loop radiative corrections mediated by the massive $SU(3)$ gauge bosons. This BSM model is able to accommodate the known spectrum of quark masses and mixing in a $4\times 4$ non-unitary $V_{CKM}$ as well as the charged lepton masses. The explored parameter space region provide the vector-like fermion masses: $M_D \approx 914.365 $GeV, $M_U \approx 1.5 $TeV, $M_E \approx 5.97 $TeV, $SU(3)$ family gauge boson masses of $\mathcal{O} (1-10) $TeV, the neutrino masses $(m_1, m_2, m_3, m_4, m_5, m_6, m_7, m_8)= (0,0.0085, 0.049, 0.22, 3.21 , 1749.96,1\times 10^8, 1\times 10^9 ) $eV, with the squared neutrino mass differences: $m_2^2-m_1^2 \approx 7.23 \times 10^{-5} \text{eV}^2$, $m_3^2-m_1^2 \approx 2.4 \times 10^{-3} \text{eV}^2$, $m_4^2-m_1^2 \approx 0.049 \text{eV}^2$, $m_5^2-m_1^2 \approx 10.3 \text{eV}^2$. We also show the corresponding $U_{PMNS}$ lepton mixing matrix. However, the neutrino mixing angles are extremely sensitive to parameter space region, and an improved and detailed analysis is in progress.