Predictivity of Neutrino Mass Sum Rules

TL;DR

This paper develops a formalism to analyze how corrections affect neutrino mass sum rules, demonstrating that their predictions remain largely stable and thus confirming their robustness in lepton flavor models.

Contribution

It introduces a model-independent perturbative approach to quantify corrections to neutrino mass sum rules, enhancing the understanding of their stability and predictivity.

Findings

Predictions from neutrino mass sum rules are generally stable against corrections.

The formalism allows for quantifying modifications to sum rule predictions.

Neutrino mass sum rules remain predictive despite small perturbations.

Abstract

Correlations between light neutrino observables are arguably the strongest predictions of lepton avour models based on (discrete) symmetries, except for the very few cases which unambiguously predict the full set of leptonic mixing angles. A subclass of these correlations are neutrino mass sum rules, which connect the three (complex) light neutrino mass eigenvalues among each other. This connection constrains both the light neutrino mass scale and the Majorana phases, so that mass sum rules generically lead to a nonzero value of the lightest neutrino mass and to distinct predictions for the e ective mass probed in neutrinoless double beta decay. However, in nearly all cases known, the neutrino mass sum rules are not exact and receive corrections from various sources. We introduce a formalism to handle these corrections perturbatively in a model-independent manner, which overcomes issues present in earlier approaches. Our ansatz allows us to quantify the modi cation of the predictions derived from neutrino mass sum rules. We show that, in most cases, the predictions are fairly stable: while small quantitative changes can appear, they are generally rather mild. We therefore establish the predictivity of neutrino mass sum rules on a level far more general than previously known.