CERN Accelerating science

Article
Report number arXiv:0806.0717 ; SI-HEP-2008-10 ; CERN-PH-TH-2008-117 ; CERN-PH-TH-2008-117 ; SI-HEP-2008-10
Title Neutrino-Mass Hierarchies and Non-linear Representation of Lepton-Flavour Symmetry
Author(s) Feldmann, Thorsten (Siegen U.) ; Mannel, Thomas (Siegen U. ; CERN)
Publication 2008
Imprint 05 Jun 2008
Number of pages 17
In: Phys. Rev. D 78 (2008) 036009
DOI 10.1103/PhysRevD.78.036009
Subject category Particle Physics - Phenomenology
Abstract Lepton-flavour symmetry in the Standard Model is broken by small masses for charged leptons and neutrinos. Introducing neutrino masses via dimension-5 operators associated to lepton-number violation at a very high scale, the corresponding coupling matrix may still have entries of order 1, resembling the situation in the quark sector with large top Yukawa coupling. As we have shown recently, in such a situation one may introduce the coupling matrices between lepton and Higgs fields as non-linear representations of lepton-flavour symmetry within an effective-theory framework. This allows us to separate the effects related to the large mass difference observed in atmospheric neutrino oscillations from those related to the solar mass difference. We discuss the cases of normal or inverted hierarchical and almost degenerate neutrino spectrum, give some examples to illustrate minimal lepton-flavour violation in radiative and leptonic decays, and also provide a systematic definition of next-to-minimal lepton-flavour violation within the non-linear framework.



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 Record created 2008-06-05, last modified 2023-03-20


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