Measurement of the Σ−→ne−¯v and Σ−→ nμ−¯v rates

Approximately 106 Σ± decays of the stopping K− film (80 cm Saclay HBC) have been measured with the Heidelberg KONRAD-system1. This system is capable of detecting about 75% of the Σ−→ ne−¯v decays. In addition, about 106 pictures have been scanned for Σ± leptonic decays with secondary particle momenta below 80 MeV/c. This covers about 15% of the lepton spectrum. The data yield the following branching ratios: