Neutrinoless tau-lepton decays into either three leptons (τ - → ℓ 1 - ℓ 2 ℓ 3 ) or one lepton and one K S 0 meson(τ - → ℓ - K S 0 ) where lepton ℓ means either an electron or muon, have been searched for using 48.6 fb -1 of data collected with the Belle detector at the KEKB e + e - collider. No evidence for candidate decays are found in any channel. Therefore we set 90% confidence level upper limits on the branching fraction for 8 different decay modes. These limits are more stringent than those set previously and reach to the 10 -7 level.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Nuclear and High Energy Physics