General considerations on lepton mass matrices

Andrea Romanino, Yakefu Reyimuaji
2018 Proceedings of Corfu Summer Institute 2017 "Schools and Workshops on Elementary Particle Physics and Gravity" — PoS(CORFU2017)   unpublished
We classify the flavour groups and representations providing, in the symmetric limit, an approximate description of lepton masses and mixings. We assume that the light neutrinos are of Majorana type and that the flavour symmetry directly constrains their mass matrix. The representations can be characterised by the dimension, type (real, pseudoreal, complex), and equivalence of its irreducible components, and in terms of such a classification we find only six viable cases. It turns out that the
more » ... eutrinos are always either anarchical or have an inverted hierarchical spectrum. Therefore, if the hint of a normal hierarchical spectrum were confirmed, we would conclude (under the above assumption) that symmetry breaking effects must play a primary role in the understanding of neutrino flavour observables.
doi:10.22323/1.318.0024 fatcat:i3meiw5gsbf5tfvx74b7biwkru