The special Two zeros texture based on $A_4$ symmetry and perturbation method

TL;DR

This paper investigates a specific two-zero neutrino mass matrix with $A_4$ symmetry, using perturbation methods to reconcile theoretical predictions with experimental neutrino mixing data, especially the non-zero $ heta_{13}$.

Contribution

It introduces a perturbation approach to modify a symmetric neutrino mass matrix, enabling compatibility with experimental neutrino mixing angles and mass ordering.

Findings

Only the case with $ ext{Re}( ext{perturbation})<0$ matches experimental data.

Predicts inverted mass hierarchy for the viable case.

Deviations in $ heta_{23}$ align with observations.

Abstract

The current study aimed to investigate the special case of two zeros in a Majorana neutrino mass matrix based on $A_4$ symmetry, where charged lepton mass matrix is diagonal. The texture $M_\nu^{S_7}$ with $(\mu, \mu)$ and $(\tau,\tau)$ vanishing element of mass matrix has magic and $\mu-\tau$ symmetry, with a tribimaximal form of the mixing matrix which leads to $\theta_{13}=0$ that it is not consistent with experimental data and does not seem to be allowed. Since $\theta_{13}$ is small compared to other neutrino mixing angles, we show that $\theta_{13}$, and $\delta$ could be obtained by using a complex symmetrical perturbation in the mass basis and also could be shown that $\delta m^2\equiv~m_2^2-m^2_1\neq0$ affecting the atmospheric mixing angle. We find that for the complex perturbation mass matrix, only the results of the case I, $\Delta<0$ and $\textit{Re}(\alpha)<0$, are consistent with experimental data. Furthermore, the allowed range of our parameter space and complex element of perturbation are found which led to finding the deviation of $\theta_{23}$ from $45^\circ$ where this deviation is in line with the experimental data which indicate the accuracy of our model and its results. Our prediction is inverted mass ordering in the Case I. The results of the case II, $\Delta>0$ and $\textit{Re}(\alpha)>0$, are ruled out.