Neutrino Mass Sum-rules in Flavor Symmetry Models

TL;DR

This paper examines specific neutrino mass sum-rules derived from flavor symmetry models, analyzing their implications for neutrino mass observables and how they can distinguish between different theoretical models.

Contribution

It provides analytical and graphical analysis of neutrino mass sum-rules from flavor symmetries, highlighting their potential to differentiate models beyond oscillation data.

Findings

Sum-rules restrict the parameter space of neutrino observables.

Analytical expressions for observables are derived.

Deviations from sum-rules can reveal new features.

Abstract

Four different neutrino mass sum-rules have been analyzed: these frequently arise in flavor symmetry models based on the groups A_4, S_4 or T', which are often constructed to generate tri-bimaximal mixing. In general, neutrino mass can be probed in three different ways, using beta decay, neutrino-less double beta decay and cosmology. The general relations between the corresponding three neutrino mass observables are well known. The sum-rules lead to relations between the observables that are different from the general case and therefore only certain regions in parameter space are allowed. Plots of the neutrino mass observables are given for the sum-rules, and analytical expressions for the observables are provided. The case of deviations from the exact sum-rules is also discussed, which can introduce new features. The sum-rules could be used to distinguish some of the many models in the literature, which all lead to the same neutrino oscillation results.