Parametrizing the lepton mixing matrix in terms of deviations from tri-bimaximal mixing

TL;DR

This paper introduces a new parametrization of the lepton mixing matrix based on deviations from tri-bimaximal mixing, simplifying neutrino phenomenology and aiding model comparison with experimental data.

Contribution

It presents a general parametrization of the lepton mixing matrix in terms of deviations from tri-bimaximal mixing, simplifying analysis and model testing.

Findings

Compact form of unitarity triangles and oscillation formulas

Facilitates comparison of models predicting deviations

Simplifies neutrino phenomenology calculations

Abstract

We propose a parametrization of the lepton mixing matrix in terms of an expansion in powers of the deviations of the reactor, solar and atmospheric mixing angles from their tri-bimaximal values. We show that unitarity triangles and neutrino oscillation formulae have a very compact form when expressed in this parametrization, resulting in considerable simplifications when dealing with neutrino phenomenology. The parametrization, which is completely general, should help to establish possible relations between the deviations of the reactor, solar and atmospheric mixing angles from their tri-bimaximal values, and hence enable models which predict such relations to be more directly compared to experiment.