The KARMEN Time Anomaly: Search for a Neutral Particle of Mass 33.9 MeV in Pion Decay

Abstract

We have searched for the pion decay pi^+ --> mu^+ X, where X is a neutral particle of mass 33.905 MeV. This process was suggested by the KARMEN Collaboration to explain an anomaly in their observed time distribution of neutrino induced reactions. Having measured the muon momentum spectrum of charged pions decaying in flight, we find no evidence for this process and place an upper limit on the branching fraction eta leq 6.0 * 10^{-10} of such a decay at a 95% confidence level.

17 pages including 4 for figures

References in corpus (9)

• A Unified Approach to the Classical Statistical Analysis of Small Signals
• Remarks on the KARMEN Anomaly
• A Supersymmetric Resolution of the KARMEN Anomaly
• Possible pre-LEP200 SUSY threshold signals
• Search for Exotic Muon Decays
• Search for the Hypothetical pi -> mu x Decay
• Exotic muon decays and the KARMEN anomaly
• Search for a 33.9 MeV/c^2 Neutral Particle in Pion Decay
• Laboratory Constraints on a 33.9 MeV/c^2 Isosinglet Neutrino: Status and Perspectives

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