Author/Authors :
M. Daum، نويسنده , , R. Frosch، نويسنده , , W. Hajdas، نويسنده , , M. Janousch، نويسنده , , P.-R. Kettle، نويسنده , , St. Ritt، نويسنده , , Z.G. Zhao، نويسنده ,
Abstract :
We have measured the muon momentum distribution in charged pion decay in flight in order to search for a small branching fraction η of pion decays π+ → μ+ + X, in which a heavy neutral particle X with a mass of 33.9 MeV would be emitted. The upper limit of η at a confidence level of 95% is found to be 2.6×10−8.
