A Bayesian comparison of U(1) lepton flavour models

Abstract

Whether the anarchical ansatz or more symmetric structures best describe the neutrino parameters is a long standing question that underwent a revival of interest after the discovery of a non- vanishing reactor angle and the indication of a non-maximal atmospheric angle. In this letter, a Bayesian statistical approach is adopted in order to analyse and compare the two hypotheses within the context of U(1) flavour models. We study the constraints on individual model parameters and perform model comparison: the results elect constructions with built-in hierarchies among the matrix elements as preferred over the anarchical ones, with values of the evidence that depends slightly on whether the U(1) charges are also considered as free parameters or not, and on the priors used.