Next-to-tribimaximal mixing against CP violation and baryon asymmetry signs

TL;DR

This paper examines next-to-tribimaximal mixing patterns in neutrino physics, showing how recent CP violation measurements constrain models and predicting a specific pattern consistent with leptogenesis and future experimental data.

Contribution

It demonstrates that recent CP phase constraints can select a unique NTBM pattern compatible with leptogenesis and predicts correlations between CP phase and atmospheric mixing angle.

Findings

A unique NTBM pattern is identified within 3σ constraints.

Predicted correlation between CP phase and atmospheric angle octant.

Future measurements can confirm the predicted CP phase and angle relationship.

Abstract

Four next-to-tribimaximal (NTBM) mixing patterns are widely considered as the feasible candidates for the observed leptonic mixing structure. With the recent measurements from T2K, as well as intensive global fits, the interval of $\sin\delta_{ CP} > 0$ for the Dirac CP-violating phase is persistently small in the normal ordering while $\sin\delta_{ CP} < 0$ is successively obtained up to $3\sigma$ level in the inverted ordering. In this paper, we advocate the fitting results of Dirac CP-violating phase as a constraint, and show that, it can basically rule out half of the regions allowed by the constraint from three mixing angles only. In addition, given the small $\sin\delta_{ CP} > 0$ interval, we find that a unique NTBM pattern can be selected out of the four candidates within $3\sigma$ uncertainty of the latest NuFIT 5.1, when the patterns are exposed to a Yukawa texture-independent leptogenesis for the baryon asymmetry of the Universe. For the surviving pattern, we find an interesting correlation between the Dirac CP-violating phase and the octant of atmospheric angle $\theta_{23}$ , where $\theta_{23}>45^\circ$ can be predicted once $5\pi/6 < \delta_{CP} <\pi$ in the normal ordering can be confirmed in the future measurements.