A light sterile neutrino from Friedberg–Lee symmetry

Xiao-Gang He,Wei Liao

doi:10.1016/j.physletb.2013.11.039

Abstract

Light sterile neutrinos of mass about an eV with mixing U˜ls of a few percent to active neutrinos may solve some anomalies shown in experimental data related to neutrino oscillation. How to have light sterile neutrinos is one of the theoretical problems which have attracted a lot of attentions. In this article we show that such an eV scale light sterile neutrino candidate can be obtained in a seesaw model in which the right-handed neutrinos satisfy a softly-broken Friedberg–Lee (FL) symmetry. In this model a right-handed neutrino is guaranteed by the FL symmetry to be light comparing with other two heavy right-handed neutrinos. It can be of eV scale when the FL symmetry is softly broken and can play the role of eV scale sterile neutrino needed for explaining the anomalies of experimental data. This model predicts that one of the active neutrino is massless. We find that this model prefers inverted hierarchy mass pattern of active neutrinos than normal hierarchy. An interesting consequence of this model is that realizing relatively large |U˜es| and relatively small |U˜μs| in this model naturally leads to a relatively small |U˜τs|. This interesting prediction can be tested in future atmospheric or solar neutrino experiments.

Highlights

Experiments have confirmed the existence of three active neutrinos, νe, νμ and ντ participating the usual weak interactions and mixing with each other, beyond reasonable doubt
In summary we have shown that seesaw mechanism plus FL symmetry provide a natural mechanism for having a light sterile neutrino
With soft-breaking of FL symmetry in Majorana mass sector, an eV scale right-handed neutrino coupled to other light neutrinos can emerge and it can play the role of eV scale sterile neutrino required for explaining experiments such as LSND, MiniBooNE, reactor flux anomaly and Gallium radioactive source experiment

Summary

A Light Sterile Neutrino from Friedberg-Lee Symmetry

Light sterile neutrinos of mass about an eV with mixing Uls of a few percent to active neutrinos may solve some anomalies shown in experimental data related to neutrino oscillation. In this model a right-handed neutrino is guaranteed by the FL symmetry to be light comparing with other two heavy right-handed neutrinos It can be of eV scale when the FL symmetry is softly broken and can play the role of eV scale sterile neutrino needed for explaining the anomalies of experimental data. This model predicts that one of the active neutrino is massless. An interesting consequence of this model is that realizing relatively large |Ues| and relatively small |Uμs| in this model naturally leads to a relatively small |Uτs| This interesting prediction can be tested in future atmospheric or solar neutrino experiments

Introduction

Findings

Conclusions