Phenomenological Study of Residual Z^s_2 and Zbar^s_2 Symmetries

TL;DR

This study investigates how residual Z2 symmetries influence neutrino oscillation predictions and how upcoming experiments can distinguish these symmetries based on measured parameters.

Contribution

It provides a detailed phenomenological analysis of residual Z2 symmetries' effects on neutrino oscillation observables and proposes experimental strategies to differentiate them.

Findings

Residual symmetries predict distinct CP phase distributions.

Neutrino experiments can resolve the neutrino mass hierarchy.

Symmetries can be distinguished if the atmospheric angle is non-maximal.

Abstract

The phenomenological consequences of the residual Z^s_2 and Zbar^s_2 symmetries are explored in detail. With a precisely measured value of the reactor angle, these two residual symmetries predict distinct distributions for the Dirac CP phase and the atmospheric angle, which leads to the possibility of identifying them at neutrino experiments. For both symmetries, it is possible to resolve the neutrino mass hierarchy in most of the parameter space, and they can be distinguished from one another if the true residual symmetry is Z^s_2 and the atmospheric angle is non-maximal. These results are obtained using an equally split schedule: a 1.5-year run of neutrinos and a 1.5-year run of antineutrinos at NOvA together with a 2.5-year run of neutrinos and a 2.5-year run of antineutrinos at T2K. This schedule can significantly increase and stabilize the sensitivities to the mass hierarchy and the octant of the atmospheric angle with only a moderate compromise to the sensitivity of distinguishing Z^s_2 and Zbar^s_2.