Renormalization Group Running of the Neutrino Mass Operator in Extra Dimensions

TL;DR

This paper investigates how neutrino masses and mixing parameters evolve with energy in models with extra dimensions, revealing significant running effects and compatibility of certain mixing patterns with experimental data.

Contribution

It derives the beta functions for neutrino mass operators in extra-dimensional models and analyzes the RG running of neutrino parameters, including the impact on mixing patterns.

Findings

Power-law behavior in RG running of neutrino parameters

Large running of the mixing angle θ12, negligible for θ23 and θ13

High-energy tri-bimaximal and bimaximal mixing compatible with low-energy data

Abstract

We study the renormalization group (RG) running of the neutrino masses and the leptonic mixing parameters in two different extra-dimensional models, namely, the Universal Extra Dimensions (UED) model and a model, where the Standard Model (SM) bosons probe an extra dimension and the SM fermions are confined to a four-dimensional brane. In particular, we derive the beta function for the neutrino mass operator in the UED model. We also rederive the beta function for the charged-lepton Yukawa coupling, and confirm some of the existing results in the literature. The generic features of the RG running of the neutrino parameters within the two models are analyzed and, in particular, we observe a power-law behavior for the running. We note that the running of the leptonic mixing angle \theta_{12} can be sizable, while the running of \theta_{23} and \theta_{13} is always negligible. In addition, we show that the tri-bimaximal and the bimaximal mixing patterns at a high-energy scale are compatible with low-energy experimental data, while a tri-small mixing pattern is not. Finally, we perform a numerical scan over the low-energy parameter space to infer the high-energy distribution of the parameters. Using this scan, we also demonstrate how the high-energy \theta_{12} is correlated with the smallest neutrino mass and the Majorana phases.