Search for lepton flavor-violating decay modes $B^0 \to K_S^0\tau^\pm\ell^\mp (\ell=\mu,e)$ with hadronic $B$-tagging at Belle and Belle II

Sumitted to PubDB: 2026-03-31

Category: Physics / performance paper

Tags:

Principal Authors Meihong Liu, Tao Luo, Karim Trabelsi
Date 2026-03-31
Working group Radiative and Electroweak Penguin
Belle II Number BELLE2-PUB-PH-2026-018
Abstract We present the first search for the lepton flavor-violating decay modes $B^0 \rightarrow K_S^0 \tau^\pm \ell^\mp~(\ell=\mu, e)$ using the 711 fb$^{-1}$ and 365 fb$^{-1}$ data samples recorded by the Belle and Belle II detectors, respectively. We use a hadronic $B$-tagging technique, and search for the signal decay in the system recoiling against the fully reconstructed $B$ meson. We find no evidence for $B^0 \rightarrow K_S^0 \tau^\pm \ell^\mp$ decays and set 90% confidence level upper limits on the branching fractions in the range of $[0.8,\,3.6]\times10^{-5}$.
ArXiv https://arxiv.org/abs/2412.16470
Inspire https://inspirehep.net/literature/2862267
DOI 10.1103/yzvh-v3hm
Reference Phys.Rev.Lett. 135, 041801 (2025)
Bibtex
@article{Belle:2024kur,
    author = "Adachi, Ichiro and others",
    collaboration = "Belle, Belle-II",
    title = "{Search for Lepton-Flavor-Violating Decay Modes B0{\textrightarrow}KS0{\ensuremath{\tau}}{\ensuremath{\pm}}{\ensuremath{\ell}}{\ensuremath{\mp}} with Hadronic B Tagging at Belle and Belle~II}",
    eprint = "2412.16470",
    archivePrefix = "arXiv",
    primaryClass = "hep-ex",
    reportNumber = "Belle II Preprint 2024-031, KEK Preprint 2024-33",
    doi = "10.1103/yzvh-v3hm",
    journal = "Phys. Rev. Lett.",
    volume = "135",
    number = "4",
    pages = "041801",
    year = "2025"
}

Files

-