Search for lepton flavor violating τ− decays into ℓ−KS0 and ℓ−KS0KS0

We have searched for the lepton-flavor-violating decays τ−→ℓ−KS0 and ℓ−KS0KS0 (ℓ=e or μ), using a data sample of 671 fb−1 collected with the Belle detector at the KEKB asymmetric-energy e+e− collider. No evidence for a signal was found in any of the decay modes, and we set the following upper limits for the branching fractions: B(τ−→e−KS0)<2.6×10−8, B(τ−→μ−KS0)<2.3×10−8, B(τ−→e−KS0KS0)<7.1×10−8 and B(τ−→μ−KS0KS0)<8.0×10−8 at the 90% confidence level.