Cobimaximal Neutrino Mixing from $A_4$ and its Possible Deviation

TL;DR

This paper explores how deviations from cobimaximal neutrino mixing, achieved via $A_4$ symmetry, can occur when the neutrino mass matrix's diagonalization matrix shifts from orthogonal to unitary, impacting phenomenological predictions.

Contribution

It introduces a framework to analyze deviations in cobimaximal neutrino mixing patterns by replacing the orthogonal matrix with a unitary matrix within the $A_4$ symmetry context.

Findings

Deviations from cobimaximal mixing are characterized by the unitary matrix modifications.

Potential impacts on neutrino oscillation parameters are discussed.

The study provides a basis for future phenomenological analyses.

Abstract

It has recently been shown that the phenomenologically successful pattern of cobimaximal neutrino mixing ($\theta_{13} \neq 0$, $\theta_{23} = \pi/4$, and $\delta_{CP} = \pm \pi/2$) may be achieved in the context of the non-Abelian discrete symmetry $A_4$, if the neutrino mass matrix is diagonalized by an orthogonal matrix ${\cal O}$. We study how this pattern would deviate if ${\cal O}$ is replaced by an unitary matrix.