Neutrino mass ordering and \mu-\tau reflection symmetry breaking

TL;DR

This paper investigates how neutrino mass ordering and - reflection symmetry breaking are related, showing that current data constrain symmetry breaking effects independently of specific models.

Contribution

It demonstrates that - reflection symmetry breaking effects are model-independently constrained by current experimental data, regardless of mass ordering.

Findings

Symmetry breaking effects are constrained at the 3cc level.

Mass relabeling preserves Majorana neutrino mass matrix.

Reordering mixing matrix columns affects mixing angles.

Abstract

If the neutrino mass spectrum turns out to be m^{}_3 < m^{}_1 < m^{}_2, one may choose to relabel it as m^{\prime}_1 < m^{\prime}_2 < m^{\prime}_3 such that all the masses of fundamental fermions with the same electrical charges are in order. In this case the columns of the 3\times 3 lepton flavor mixing matrix U should be reordered accordingly, and the resulting pattern U^\prime may involve one or two large mixing angles in the standard parametrization or its variations. Since the Majorana neutrino mass matrix keeps unchanged in such a mass relabeling, a possible \mu-\tau reflection symmetry is respected in this connection and its breaking effects are model-independently constrained at the 3\sigma level by using current experimental data.