An eigenvector based approach to neutrino mixing

TL;DR

This paper introduces a model-independent eigenvector-based method to analyze neutrino mixing, revealing that deviations from tribimaximal mixing can be naturally explained as small perturbations, suggesting a hybrid nature of the neutrino mass matrix.

Contribution

It presents a novel eigenvector expansion approach for neutrino mass matrices, facilitating analysis of deviations from tribimaximal mixing in a model-independent way.

Findings

Deviations from tribimaximal mixing are small perturbations of eigenvectors.

The approach applies to different neutrino mass generation mechanisms.

Observed mixing patterns can be explained by a hybrid neutrino mass matrix.

Abstract

We propose a model-independent analysis of the neutrino mass matrix through an expansion in terms of the eigenvectors defining the lepton mixing matrix, which we show can be parametrized as small perturbations of the tribimaximal mixing eigenvectors. This approach proves to be powerful and convenient for some aspects of lepton mixing, in particular when studying the sensitivity of the mass matrix elements to departures from their tribimaximal form. In terms of the eigenvector decomposition, the neutrino mass matrix can be understood as originating from a tribimaximal dominant structure with small departures determined by data. By implementing this approach to cases when the neutrino masses originate from different mechanisms, we show that the experimentally observed structure arises very naturally. We thus claim that the observed deviations from the tribimaximal mixing pattern might be interpreted as a possible hint of a ``hybrid'' nature of the neutrino mass matrix.