Improved limits on nuebar emission from mu+ decay

Abstract

We investigated mu+ decays at rest produced at the ISIS beam stop target. Lepton flavor (LF) conservation has been tested by searching for \nueb via the detection reaction p(\nueb,e+)n. No \nueb signal from LF violating mu+ decays was identified. We extract upper limits of the branching ratio for the LF violating decay mu+ -> e+ \nueb νcompared to the Standard Model (SM) mu+ -> e+ nue numub decay: BR < 0.9(1.7)x10^{-3} (90%CL) depending on the spectral distribution of \nueb characterized by the Michel parameter rho=0.75 (0.0). These results improve earlier limits by one order of magnitude and restrict extensions of the SM in which \nueb emission from mu+ decay is allowed with considerable strength. The decay \mupdeb as source for the \nueb signal observed in the LSND experiment can be excluded.

10 pages, including 1 figure, 1 table

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Cited by in corpus (12)

• Status of global fits to neutrino oscillations
• Sterile neutrino oscillations after first MiniBooNE results
• Explaining LSND by a decaying sterile neutrino
• Neutrinoless double beta decay in chiral effective field theory: lepton number violation at dimension seven
• Neutrino Mass and New Physics
• Exploring a Non-Minimal Sterile Neutrino Model Involving Decay at IceCube and Beyond
• Neutrinos Have Mass - So What?
• Neutrino Physics: Open Theoretical Questions
• A Three-Flavor, Lorentz-Violating Solution to the LSND Anomaly
• Systematic Approach to Gauge-Invariant Relations between Lepton Flavor Violating Processes
• Low energy neutrino scattering measurements at future Spallation Source facilities
• Concluding Remarks/Summary