2004/09/30 by Gary Prézeau, Andriy Kurylov · 19 citations
Mathematics · Physics and Astronomy · #Algorithm #Astrophysics and Cosmic Phenomena #Branching fraction #Mathematical analysis #Mathematics #Neutrino #Neutrino Physics Research #Order (exchange) #Particle physics #Particle physics theoretical and experimental studies #Physics #Standard Model (mathematical formulation) #Upper and lower bounds #hep-ex #hep-ph
paper · pdf · doi:10.1103/physrevlett.95.101802
published in Physical Review Letters 95(10), 101802 (American Physical Society) · Accepted for publication in PRL
arxiv created 2005/07/28 · openalex publication_date 2005/09/01 · openalex created_date 2016/06/24 · arxiv updated 2016/08/16 · openalex updated_date 2026/08/05
In this Letter, we show that upper limits on the neutrino mass translate into upper limits on the class of neutrino-matter interactions that can generate loop corrections to the neutrino mass matrix. We apply our results to \ensuremathμ and \ensuremathπ decays and derive model-independent limits on six of the ten parameters used to parametrize contributions to \ensuremathμ decay that do not belong to the standard model. These upper limits provide improved constraints on the five Michel parameters, \ensuremathρ,\ensuremathξ^\ensuremath',\ensuremathξ^\ensuremath'\ensuremath',\ensuremathα,\ensuremathα^\ensuremath', that exceed Particle Data Group constraints by at least one order of magnitude. For \ensuremathπ0\ensuremath→\ensuremathν\ensuremathν we find, for the branching ratio, B(\ensuremathπ0\ensuremath→\ensuremathν\ensuremathν)<10^\ensuremath-10.