부산대학교 도서관

Abstract Charged lepton flavor violation is forbidden in the Standard Model but possible in several new physics scenarios. In many of these models, the radiative decays τ ± → ℓ ± γ (ℓ = e, μ) are predicted to have a sizeable probability, making them particularly interesting channels to search at various experiments. An updated search via τ ± → ℓ ± γ using full data of the Belle experiment, corresponding to an integrated luminosity of 988 fb −1, is reported for charged lepton flavor violation. No significant excess over background predictions from the Standard Model is observed, and the upper limits on the branching fractions, B $$ \mathcal{B} $$ (τ ± → μ ± γ) ≤ 4.2 × 10 −8 and B $$ \mathcal{B} $$ (τ ± → e ± γ) ≤ 5.6 × 10 −8, are set at 90% confidence level.