Realization of the minimal extended seesaw mechanism and the TM2 type neutrino mixing

Abstract

We construct a neutrino mass model based on the flavour symmetry group A4×C4×C6×C2 which accommodates a light sterile neutrino in the minimal extended seesaw (MES) scheme. Besides the flavour symmetry, we introduce a U(1) gauge symmetry in the sterile sector and also impose CP symmetry. The vacuum alignments of the scalar fields in the model spontaneously break these symmetries and lead to the construction of the fermion mass matrices. With the help of the MES formulas, we extract the light neutrino masses and the mixing observables. In the active neutrino sector, we obtain the TM2 mixing pattern with non-zero reactor angle and broken μ-τ reflection symmetry. We express all the active and the sterile oscillation observables in terms of only four real model parameters. Using this highly constrained scenario we predict $$ {\sin}^2{\theta}_{23}={0.545}_{-0.004}^{+0.003},\sin \delta =-{0.911}_{-0.005}^{+0.006},{\left|{U}_{e4}\right|}^2={0.029}_{-0.008}^{+0.009},{\left|{U}_{\mu 4}\right|}^2={0.010}_{-0.003}^{+0.003}\kern0.5em \mathrm{and}\kern0.5em {\left|{U}_{\tau 4}\right|}^2={0.006}_{-0.002}^{+0.002} $$ sin 2 θ 23 = 0.545 − 0.004 + 0.003 , sin δ = − 0.911 − 0.005 + 0.006 , U e 4 2 = 0.029 − 0.008 + 0.009 , U μ 4 2 = 0.010 − 0.003 + 0.003 and U τ 4 2 = 0.006 − 0.002 + 0.002 which are consistent with the current data.

Effect of Sterile Neutrino on Low-Energy Processes in Minimal Extended Seesaw With Δ(96) Symmetry and TM1 Mixing

“…This field has a coupling with the heavy right-handed neutrino fields that are present in the type I seesaw [34,35]. Thus, the Lagrangian in this MES model can be obtained as [36]…”

“…Since the right-handed neutrinos are much heavier than the electroweak scale as in the case of the type I seesaw, they should be decoupled at low scales. Effectively, the full 7 × 7 matrix can be block diagonalized into a 4 × 4 neutrino mass matrix as follows [36]: Assuming M S > M D , the active neutrino mass matrix of Eq. 3 takes the form…”

$B-L$ model with $A_4\times Z_3\times Z_4$ symmetry for $3+1$ active$-$sterile neutrino mixing

“…The mentioned sterile neutrino is an SU (2) L singlet which does not contribute to the weak interactions but mix with the active neutrinos that can be probed in the oscillation experiments. Among four neutrino schemes, the one with three active neutrinos and one sterile neutrino (called 3+1 scheme) is preferred because the 1+3 scenario in which the three active neutrinos are in eV scale and the sterile neutrino is lighter than the active neutrinos is disfavored by cosmology and the 2+2 scheme is not compatible with the solar and the atmospheric data [15,16].…”

“…At present, the neutrino mass squared differences and the mixing angles in the three neutrino framework[1] and (3+1) neutrino framework [14,16], for the best-fit values and 3σ range, are given in Table I. One outstanding feature of discrete symmetries is imposed to explain the neutrino oscillation data which have been presented in different works.…”

“…In Refs. [16,[30][31][32][33][34][35] the active-sterile neutrino mass and mixing have been considered with A 4 symmetry with non minimal scalar sector and many SU (2) L Higgs doublets, thus there are substantial differences between previous works and our present work. For instance, in Refs.…”