Abstract
An experiment to search for the →μe and →ee decays and to measure the branching ratio of the →μμ decay was performed at the KEK 12-GeV Proton Synchrotron. The single-event sensitivity of the present experiment for these channels was around 4×. No event was observed in the fiducial region for the →μe decay and one event, which could not be distinguished from the background, was observed in the fiducial region for the →ee decay. The obtained upper limits on the branching ratios at 90% confidence level were B(→μe)<9.4× and B(→ee)<1.6×. The branching ratio of the →μμ decay was obtained to be [7.9±0.6 (stat ±0.2 (syst)]× based on 179 events in the fiducial region. Using 18 events with the effective mass >470 MeV / in the sample for the →ee decay search, the branching ratio of the → decay was estimated to be [6±2 (stat) ±1 (syst)]× for >470 MeV/ and [7±3 (stat)±2(syst)]× for >480 MeV/.
- Received 30 September 1994
DOI:https://doi.org/10.1103/PhysRevD.51.2061
©1995 American Physical Society