Testing solar lepton mixing sum rules in neutrino oscillation experiments

TL;DR

This paper derives and analyzes solar lepton mixing sum rules in neutrino oscillation experiments, exploring their testability with upcoming experimental data and their connection to discrete family symmetries.

Contribution

It provides a simple derivation of solar sum rules for arbitrary mixing angles and phases, and assesses their experimental testability with future neutrino experiments.

Findings

Sum rules can be tested with next-generation experiments

Certain mixing patterns are compatible with observed data

Complementarity of different experimental setups enhances testing capability

Abstract

Small discrete family symmetries such as S4, A4 or A5 may lead to simple leading-order predictions for the neutrino mixing matrix such as the bimaximal, tribimaximal or golden ratio mixing patterns, which may be brought into agreement with experimental data with the help of corrections from the charged-lepton sector. Such scenarios generally lead to relations among the parameters of the physical leptonic mixing matrix known as solar lepton mixing sum rules. In this article, we present a simple derivation of such solar sum rules, valid for arbitrary neutrino and charged lepton mixing angles and phases, assuming only {\theta}13^{\nu} = {\theta}13^e = 0. We discuss four leading-order neutrino mixing matrices with {\theta}13^{\nu} = 0 which are well motivated from family symmetry considerations. We then perform a phenomenological analysis of the scope to test the resulting four solar sum rules, highlighting the complementarity between next-generation neutrino oscillation experiments such as the reactor experiment JUNO and a superbeam experiment.