ISSN - 00319007, EISSN - 10797114, Physical Review Letters, 2004, vol. 93, p. 081803-1
Search for the Lepton-Flavor-Violating Decay τ- → μ-η at Belle
The lepton flavor violating decay τS-S → μ-η was investigated using data sample of 84.3 fb-1 accumulated with the Belle detector at KEK. The detection of η meson was observed through the decay modes of η→γγ and π+π -π0. The minimum photon energy requirement was reduced from 0.1 to 0.005 GeV, as photons from this decay were found to have softer energy distribution compared to those in η→γγ. The results show that an upper limit for branching fraction B < 3.4×10-7 at about 90% confidence level.