Search for the $B0 \to K^{∗0} \tau^{+} \tau^{-}$ decay with an hadronic tagged approach

Sumitted to PubDB: 2025-08-25

Category: Physics / performance paper

Tags: Run 1

Principal Authors Claudia Cecchi, Elisa Manoni, Stefano Moneta
Date 2025-10-07
Working group Radiative and Electroweak Penguin
Belle II Number BELLE2-PUB-PH-2025-038
Abstract We present a search for the rare flavor-changing neutral-current decay $B^{0} \to K^{∗0} \tau^{+} \tau^{−}$ with data collected by the Belle II experiment at the SuperKEKB electron-positron collider. The analysis uses a 365 fb$^{−1}$ data sample recorded at the center-of-mass energy of the $\Upsilon(4S)$ resonance. One of the $B$ mesons produced in the $\Upsilon(4S)\to B^{0}\bar{B^{0}}$ process is fully reconstructed in a hadronic decay mode, while its companion $B$ meson is required to decay into a $K^{∗0}$ and two $\tau$ leptons of opposite charge. The $\tau$ leptons are reconstructed in final states with a single electron, muon, charged pion or charged $\rho$ meson, and additional neutrinos. We set an upper limit on the branching fraction of $\mathcal{B}(B^{0}\to K^{*0}\tau^{+}\tau^{-}) < 1.8 \times 10^{−3}$ at the 90% confidence level, which is the most stringent constraint reported to date.
ArXiv https://arxiv.org/abs/2504.10042
Inspire https://inspirehep.net/literature/2911582
DOI 10.1103/v1q3-9dy8
Reference Phys.Rev.Lett. 135, 151801 (2025)
Bibtex 
@article{Belle-II:2025lwo,
    author = "Adachi, I. and others",
    collaboration = "Belle-II",
    title = "{Search for B0{\textrightarrow}K*0{\ensuremath{\tau}}+{\ensuremath{\tau}}- Decays at the Belle II Experiment}",
    eprint = "2504.10042",
    archivePrefix = "arXiv",
    primaryClass = "hep-ex",
    reportNumber = "Belle II Preprint 2025-010; KEK Preprint 2025-8",
    doi = "10.1103/v1q3-9dy8",
    journal = "Phys. Rev. Lett.",
    volume = "135",
    number = "15",
    pages = "151801",
    year = "2025"
}
Journal Phys.Rev.Lett.

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