Paolo Leo

16 September 2024
25th International Workshop on Neutrinos from Accelerators

Abstract: Rates of lepton-flavor violation in charged lepton decays are enhanced in many beyond-the-standard-model theories. The low-background samples of e+e−→τ+τ− events collected by Belle and Belle II allow world-leading searches for such decays with tau leptons. We present Belle II results for the decays τ→ℓV0, where V0 is a neutral vector meson, τ→3μ, τ→Λπ and τ→Λ¯π (which violates both baryon and lepton number conservation) using data samples up to 424 fb−1. We also present Belle searches for the charged lepton-flavor-violating (CLFV) decays Bs→ℓτ and Υ(2S)→ℓτ. We present searches for the for the baryon and lepton number violating decays D→pℓ by analyzing 921 fb−1 of data collected by Belle at and 60 MeV below the Υ(4S) resonance, and at the Υ(5S) resonance. Finally, we present a search for B0→K0Sτℓ using a combined Belle and Belle II data set.