Repressing Anarchy in Neutrino Mass Textures

TL;DR

This paper explores models of neutrino mass textures within an SU(5) GUT framework, demonstrating that relaxing certain assumptions improves agreement with experimental data and analyzing CP-violation predictions.

Contribution

It revisits and compares various U(1)_{FN} charge assignments in SU(5) models, showing that less restrictive charge patterns better fit current neutrino data.

Findings

Relaxed charge assumptions improve data fit.

Models predict distributions for CP-violating phase.

Comparison of models highlights their relative merits.

Abstract

The recent results that $\theta_{13}$ is relatively large, of the order of the previous upper bound, and the indications of a sizable deviation of $\theta_{23}$ from the maximal value are in agreement with the predictions of Anarchy in the lepton sector. The quark and charged lepton hierarchies can then be reproduced in a SU(5) GUT context by attributing non-vanishing $U(1)_{FN}$ charges, different for each family, only to the SU(5) tenplet states. The fact that the observed mass hierarchies are stronger for up quarks than for down quarks and charged leptons supports this idea. As discussed in the past, in the flexible context of $SU(5)\otimes U(1)_{FN}$, different patterns of charges can be adopted going from Anarchy to various types of hierarchy. We revisit this approach by also considering new models and we compare all versions to the present data. As a result we confirm that, by relaxing the extreme ansatz of equal $U(1)_{FN}$ charges for all SU(5) pentaplets and singlets, better agreement with the data than for Anarchy is obtained without increasing the model complexity. We also present the distributions obtained in the different models for the Dirac CP-violating phase. Finally we discuss the relative merits of these simple models.