Addressing Neutrino Mixing Models with DUNE and T2HK

TL;DR

This paper explores how upcoming neutrino experiments DUNE and T2HK can test and distinguish between different theoretical models of neutrino mixing based on discrete symmetries and sum rules relating CP violation to mixing angles.

Contribution

It analyzes the compatibility of symmetry-based neutrino mixing models with current data and assesses the potential of future experiments to differentiate among these models.

Findings

Certain symmetry models are compatible with current data.

Future experiments can discriminate between different symmetry forms.

Predictions for CP violation phase vary significantly among models.

Abstract

We consider schemes of neutrino mixing arising within the discrete symmetry approach to the well-known flavour problem. We concentrate on $3\nu$ mixing schemes in which the cosine of the Dirac CP violation phase $\delta_\mathrm{CP}$ satisfies a sum rule by which it is expressed in terms of three neutrino mixing angles $\theta_{12}$, $\theta_{23}$, and $\theta_{13}$, and a fixed real angle $\theta^\nu_{12}$, whose value depends on the employed discrete symmetry and its breaking. We consider five underlying symmetry forms of the neutrino mixing matrix: bimaximal (BM), tri-bimaximal (TBM), golden ratio A (GRA) and B (GRB), and hexagonal (HG). For each symmetry form, the sum rule yields specific prediction for $\cos\delta_\mathrm{CP}$ for fixed $\theta_{12}$, $\theta_{23}$, and $\theta_{13}$. In the context of the proposed DUNE and T2HK facilities, we study (i) the compatibility of these predictions with present neutrino oscillation data, and (ii) the potential of these experiments to discriminate between various symmetry forms.