Bayesian comparison ofU(1)lepton flavor 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 nonvanishing 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.

Distinguishing a Higgs-like dilaton scenario with a complete bosonic effective field theory basis

“…However, as adopted in the context of the so-called Minimal Flavour Violation [68][69][70][71][72][73][74][75][76][77][78][79][80][81][82], or more in general in flavour models [83][84][85][86][87][88][89][90][91][92][93][94][95][96][97][98], a strategy to reestablish scale invariance consists in enlarging the spectrum by the addition of a scalar field, χ(x), that transforms under the scale symmetry: insertion of powers of this scalar field in the Lagrangian operators then allows to recover exactly scale invariance. Once it develops a VEV, fermion and scalar masses are correctly described and the scale symmetry is spontaneously broken with the arising of the corresponding GB, the dilaton.…”

Order and anarchy hand in hand in 5D SO(10)

“…It is clear that this number has no absolute meaning and could only be useful if compared with analogous numbers obtained by analyzing other models with a similar approach. A success rate of order 0.01 is a typical outcome in this kind of analysis for the most successful models [66,94,95].…”

The minimal flavour violating axion

“…An estimation of the range of value it may acquire takes into consideration that ǫ should remain in the perturbative regime and that the value of v Φ is expected to be not so much smaller than Λ Φ (without a dynamical mechanism to explain it). In this letter, ǫ is taken in the interval [0.01, 0.3], consistently with previous studies on FN models [6,7]. The logarithm in eq.…”

“…Once the scalar field φ, typically called flavon, develops a vacuum expectation value (VEV) the flavour symmetry is spontaneously broken and the Yukawa matrices can be written in terms of powers of φ /Λ F . Fermion mass hierarchies and mixing angles can then be explained by an appropriate choice of the FN charges [2][3][4][5][6][7]. The large number of free parameters, one for each entry of the Yukawa matrices, has the drawback of lowering the predictive power of the model: any value of fermion masses and mixings can indeed be reproduced.…”