Search for the Lepton Flavor Violating Decays ${B}^{+}\ensuremath{\rightarrow}{K}^{+}{\ensuremath{\tau}}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\ell}}^{\ensuremath{\mp}}$ ($\ensuremath{\ell}=e$, $\ensuremath{\mu}$) at Belle

Open Access

Search for the Lepton Flavor Violating Decays $B^{+} \to K^{+} τ^{\pm} ℓ^{\mp}$ ( $ℓ = e$ , $μ$ ) at Belle

S. Watanuki et al. (Belle Collaboration)

Phys. Rev. Lett. 130, 261802 – Published 28 June 2023

Abstract

We present a search for the lepton flavor violating decays $B^{+} \to K^{+} τ^{\pm} ℓ^{\mp}$ , with $ℓ = (e, μ)$ , using the full data sample of $772 \times 10^{6} B \bar{B}$ pairs recorded by the Belle detector at the KEKB asymmetric-energy $e^{+} e^{-}$ collider. We use events in which one $B$ meson is fully reconstructed in a hadronic decay mode. We find no evidence for $B^{\pm} \to K^{\pm} τ ℓ$ decays and set upper limits on their branching fractions at the 90% confidence level in the $(1 - 3) \times 10^{- 5}$ range. The obtained limits are the world’s best results.

Received 13 December 2022
Accepted 4 May 2023

DOI:https://doi.org/10.1103/PhysRevLett.130.261802

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP³.

Published by the American Physical Society