TriMinimal Parametrization of the Neutrino Mixing Matrix

TL;DR

The paper introduces 'TriMinimal', a natural parametrization of the neutrino mixing matrix based on deviations from TriBiMaximal mixing, simplifying flavor probability calculations for atmospheric and astrophysical neutrinos.

Contribution

It proposes the 'TriMinimal' parametrization, expanding flavor probabilities to second order in small deviations from TriBiMaximal mixing.

Findings

Simplified expressions for atmospheric neutrino flavor probabilities.

Second-order expansion captures relevant deviations.

Demonstrates utility in astrophysical neutrino analysis.

Abstract

Current experimental data on neutrino mixing are very well described by TriBiMaximal mixing. Accordingly, any phenomenological parametrization of the MNSP matrix must build upon TriBiMaximal mixing. We propose one particularly natural parametrization, which we call "TriMinimal". The three small deviations of the PDG angles from their TriBiMaximal values, and the PDG phase, parametrize the TriMinimal mixing matrix. As an important example of the utility of this new parametrization, we present the simple resulting expressions for the flavor-mixing probabilities of atmospheric and astrophysical neutrinos. As no foreseeable experiment will be sensitive to more than second order in the small parameters, we expand these flavor probabilities to second order.