We have searched for neutrinoless τ lepton decays into ℓ and V0, where ℓ stands for an electron or muon, and V0 for a vector meson (ϕ, ω, K∗0, K¯∗0 or ρ0), using 543 fb−1 of data collected with the ...Belle detector at the KEKB asymmetric-energy e+e− collider. No excess of signal events over the expected background has been observed, and we set upper limits on the branching fractions in the range (5.9–18)×10−8 at the 90% confidence level. These upper limits are significantly more restrictive than our previous results for the ℓϕ, ℓK∗0, ℓK¯∗0 and ℓρ0 modes.
We have searched for lepton-flavor-violating τ decays with a pseudoscalar meson (η, η′ and π0) using a data sample of 401 fb−1 collected with the Belle detector at the KEKB asymmetric-energy e+e− ...collider. No evidence for these decays is found and we set the following upper limits on the branching fractions: B(τ−→e−η)<9.2×10−8, B(τ−→μ−η)<6.5×10−8, B(τ−→e−η′)<1.6×10−7, B(τ−→μ−η′)<1.3×10−7, B(τ−→e−π0)<8.0×10−8 and B(τ−→μ−π0)<1.2×10−7 at the 90% confidence level. These results improve our previously published upper limits by factors from 2.3 to 6.3.
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