Cobimaximal lepton mixing from soft symmetry breaking

Author(s)
Walter Grimus, Luis Lavoura
Abstract

Cobimaximal lepton mixing, i.e. θ23=45° and δ=±90° in the lepton mixing matrix V, arises as a consequence of SV=V⁎P, where S is the permutation matrix that interchanges the second and third rows of V and P is a diagonal matrix of phase factors. We prove that any such V may be written in the form V=URP, where U is any predefined unitary matrix satisfying SU=U⁎, R is an orthogonal, i.e. real, matrix, and P is a diagonal matrix satisfying P2=P. Using this theorem, we demonstrate the equivalence of two ways of constructing models for cobimaximal mixing—one way that uses a standard CP symmetry and a different way that uses a CP symmetry including μ–τ interchange. We also present two simple seesaw models to illustrate this equivalence; those models have, in addition to the CP symmetry, flavour symmetries broken softly by the Majorana mass terms of the right-handed neutrino singlets. Since each of the two models needs four scalar doublets, we investigate how to accommodate the Standard Model Higgs particle in them.

Organisation(s)
Particle Physics
External organisation(s)
Universidade de Lisboa
Journal
Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics
Volume
774
Pages
325-331
No. of pages
7
ISSN
0370-2693
DOI
https://doi.org/10.1016/j.physletb.2017.09.082
Publication date
11-2017
Peer reviewed
Yes
Austrian Fields of Science 2012
103012 High energy physics, 103034 Particle physics
Portal url
https://ucris.univie.ac.at/portal/en/publications/cobimaximal-lepton-mixing-from-soft-symmetry-breaking(97b562c7-45c7-48fe-99fc-d3d61e29bcab).html