2001/05/31 by Walter Grimus, W. Grimus, L. Lavoura +1 · 1 citation
Physics and Astronomy · #Neutrino Physics Research #Noncommutative and Quantum Gravity Theories #Particle physics theoretical and experimental studies #hep-ph
paper · pdf · doi:10.1088/1126-6708/2001/07/045
published as JHEP 0107:045,2001 · Latex, 15 pages; two references added and minor changes in the text; final version accepted for publication in JHEP
openalex publication_date 2001/07/30 · arxiv created 2001/08/14 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We consider lepton mixing in an extension of the Standard Model with three right-handed neutrino singlets. We require that the three lepton numbers Le, Lμ, and Lτbe separately conserved in the Yukawa couplings, and we assume that they are softly broken only by the Majorana mass matrix MR of the neutrino singlets. In this framework, where lepton-number breaking occurs at a scale much higher than the electroweak scale, deviations from family-lepton-number conservation are calculable and finite, and lepton mixing stems exclusively from MR. We then show that a discrete symmetry exists such that, in the lepton mixing matrix U, maximal atmospheric neutrino mixing together with Ue3=0 can be obtained naturally. Alternatively, if one assumes that there are two different scales in MR and that the lepton number L = Le - Lμ- Lτis conserved in between them, then maximal solar neutrino mixing follows naturally. If both the discrete symmetry and intermediate L conservation are introduced, bimaximal mixing is achieved.