Lepton Flavor Mixing and CP Symmetry

TL;DR

This paper explores how residual CP symmetries constrain lepton flavor mixing, allowing for the reconstruction of the mixing matrix and predicting CP violation phenomena based on symmetry considerations.

Contribution

It provides a general framework linking remnant CP transformations to lepton mixing parameters, including explicit forms and phenomenological implications.

Findings

Lepton mixing matrix can be reconstructed from remnant CP transformations.

Mixing angles and CP phases are fully determined by residual CP symmetries.

Conditions for maximal or vanishing CP violation are identified.

Abstract

The strategy of constraining the lepton flavor mixing from remnant CP symmetry is investigated in a rather general way. The neutrino mass matrix generally admits four remnant CP transformations which can be derived from the measured lepton mixing matrix in the charged lepton diagonal basis. Conversely, the lepton mixing matrix can be reconstructed from the postulated remnant CP transformations. All mixing angles and CP violating phases can be completely determined by the full set of remnant CP transformations or three of them. When one or two remnant CP transformations are preserved, the resulting lepton mixing matrix would depend on three real parameters or one real parameter respectively in addition to the parameters characterizing the remnant CP, and the concrete form of the mixing matrix is presented. The phenomenological predictions for the mixing parameters are discussed. The conditions leading to vanishing or maximal Dirac CP violation are studied.