Constraining {\it CP} violation in a softly broken $A_4$ symmetric Model

Abstract

To understand the mass spectra of charged lepton and neutrino $A_4$ symmetry has been proposed in addition with the Standard $SU(2)_L\times U(1)_Y$ model. We break $A_4$ symmetry softly and the deviation from the tri-bimaximal mixing arises due to Zee mechanism. In the present work, we express two mixing angles $θ_{13}$ and $θ_{23}$ in terms of a single model parameter and experimental observables, such as, mixing angle $θ_{12}$, mass squared differences $Δm^2_{21}$ and $Δm^2_{32}$. Using the experimental values of $θ_{23}$, $θ_{12}$, $Δm^2_{21}$ and $Δm^2_{32}$ we restrict the model parameter and we predict $θ_{13}$. This model gives rise to $θ_{13}\simeq 11^\circ$ if we allow $1σ$ deviation of $θ_{23}$ and $2^\circ$ deviation of $θ_{12}$ from their best fit values. Utilizing all those constraints, we explore the extent of CP violation parameter $J_{\rm CP}$ in the present model and found a value of $J_{\rm CP}\approx 2.65\times 10^{-3}$ (for $1σ$ deviation of $θ_{23}$ and $2^\circ$ deviation of $θ_{12}$) consistent with the other neutrino experimental results. We have studied the mass pattern of neutrino and neutrinoless double beta decay $(ββ_{0ν})$ parameter $|(M_ν)_{ee}|$ in this model.

16 pages, 6 eps figures,revised materials and figures, version to appear in Phys.Rev. D