Direct and semidirect approaches to lepton mixing with a massless neutrino
Abstract
We discuss the possibility of enforcing a massless Majorana neutrino in the direct and semidirect approaches to lepton mixing, in which the PMNS matrix is partly predicted by subgroups of a discrete family symmetry, extending previous group searches up to order 1535. We find a phenomenologically viable scheme for the semidirect approach based on Q(648) which contains ∆(27) and the quaternion group as subgroups. This leads to novel predictions for the first column of the PMNS matrix corresponding to a normal neutrino mass hierarchy with m _{1} = 0, and sum rules for the mixing angles and phase which are characterised by the solar angle being on the low side θ _{12} ̃ 31° and the Dirac (oscillation) CP phase δ being either about ±45° or ±π.
 Publication:

Journal of High Energy Physics
 Pub Date:
 June 2016
 DOI:
 10.1007/JHEP06(2016)147
 arXiv:
 arXiv:1605.01683
 Bibcode:
 2016JHEP...06..147K
 Keywords:

 Global Symmetries;
 Neutrino Physics;
 High Energy Physics  Phenomenology
 EPrint:
 18 pages, 1 figure, small comments added in introduction and section 3, one reference added, version matches publication in JHEP