Correlation of normal neutrino mass ordering with upper octant of $\theta^{}_{23}$ and third quadrant of $\delta$ via RGE-induced $\mu$-$\tau$ symmetry breaking

TL;DR

This paper explains the correlation between neutrino mass ordering, mixing angles, and CP phase using RGE-induced  symmetry breaking in the MSSM, matching recent experimental data.

Contribution

It provides the first comprehensive analysis of how RGE effects can naturally produce observed neutrino mixing patterns and mass ordering in both Majorana and Dirac neutrino scenarios.

Findings

Normal mass ordering is favored at 3sigma

Best-fit 23; 23 in higher octant and third quadrant

RGE-induced symmetry breaking explains experimental observations

Abstract

The recent global analysis of three-flavor neutrino oscillation data indicates that the {\it normal} neutrino mass ordering is favored over the inverted one at the $3\sigma$ level, and the best-fit values of the largest neutrino mixing angle $\theta^{}_{23}$ and the Dirac CP-violating phase $\delta$ are located in the higher octant and the third quadrant, respectively. We show that all these important issues can be naturally explained by the $\mu$-$\tau$ reflection symmetry breaking of massive neutrinos from a superhigh energy scale down to the electroweak scale due to the one-loop renormalization-group equations (RGEs) in the minimal supersymmetric standard model (MSSM). The complete parameter space is explored {\it for the first time} in both Majorana and Dirac cases, by allowing the smallest neutrino mass $m^{}_1$ and the MSSM parameter $\tan\beta$ to vary in their reasonable regions.