2004/09/30 by S. T. Petcov, S.T. Petcov, W. Rodejohann +1
Physics and Astronomy · #Astrophysics and Cosmic Phenomena #CP violation #Electron #Leptogenesis #Lepton #MAJORANA #Mass matrix #Mixing (physics) #Neutrino #Neutrino Physics Research #Neutrino oscillation #Nuclear physics #Particle physics #Particle physics theoretical and experimental studies #Physics #Physics beyond the Standard Model #Pontecorvo–Maki–Nakagawa–Sakata matrix #Quantum mechanics #Sterile neutrino #hep-ph
paper · pdf · doi:10.1103/physrevd.71.073002
published as Phys.Rev.D71:073002,2005 · 26 pages, 3 figures. Comments and references added, to appear in PRD
arxiv created 2005/03/09 · openalex publication_date 2005/04/08 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
The Pontecorvo-Maki-Nakagawa-Sakata neutrino mixing matrix is given, in general, by the product of two unitary matrices associated with the diagonalization of the charged lepton and neutrino mass matrices. Assuming that the active flavor neutrinos possess a Majorana mass matrix which is diagonalized by a bimaximal mixing matrix, we give the allowed forms of the charged lepton mixing matrix and the corresponding implied forms of the charged lepton mass matrix. We then assume that the origin of bimaximal mixing is a weakly broken flavor symmetry corresponding to the conservation of the nonstandard lepton charge L^\ensuremath'=Le\ensuremath-L_\ensuremathμ\ensuremath-L_\ensuremathτ. The latter does not predict, in general, the atmospheric neutrino mixing to be maximal. We study the impact of this fact on the allowed forms of the charged lepton mixing matrix and on the neutrino mixing observables, analyzing the case of CP violation in detail. When compared with the case of exact bimaximal mixing, the deviations from zero Ue3 and from maximal atmospheric neutrino mixing are typically more sizable if one assumes just L^\ensuremath' conservation. In fact, |Ue3|2 can be as small as 0.007 and atmospheric neutrino mixing can take any value inside its currently allowed range. We discuss under which conditions the atmospheric neutrino mixing angle is larger or smaller than \ensuremathπ/4. We present also a simple seesaw realization of the implied light neutrino Majorana mass matrix and consider leptogenesis in this scenario.