Search for lepton-flavor-violating τ decays into a lepton and a vector meson using the full Belle data sample

Abstract

Charged-lepton-flavor-violation is predicted in several new physics scenarios. We update the analysis of τ lepton decays into a light charged lepton (ℓ = e± or μ±) and a vector meson (V0 = ρ0, ϕ, ω, K*0, or overline{K} *0) using 980 fb−1 of data collected with the Belle detector at the KEKB collider. No significant excess of such signal events is observed, and thus 90% credibility level upper limits are set on the τ → ℓV0 branching fractions in the range of (1.7–4.3) × 10−8. These limits are improved by 30% on average from the previous results.