{
  "abstract": "We present the first search for $B^0 \\to K^0_{\\rm S} τ^+τ^-$ decays. We look for signal decays in $B^0\\bar B^0$ events produced in asymmetric-energy electron-positron collisions. This work uses samples from the Belle and Belle~II detectors, comprising 1.16 billion $Υ(4S)$ events. In $Υ(4S)\\to B^0\\bar{B}^0$ decays, the non-signal $\\bar{B}^0$ meson is fully reconstructed in a hadronic channel. For the signal $B^0$ meson, $τ$-lepton decays into final states with a single charged particle are selected. We observe no evidence for the signal and set an upper limit on the branching fraction $\\mathcal{B}(B^0\\to K^0_{\\rm S} τ^+τ^-) < 8.3 \\times 10^{-4}$ at the 90\\% confidence level. Combining this with the recent measurement of the isospin-partner decay $B^+\\to K^+τ^+τ^-$, we determine an upper limit $\\mathcal{B}(B\\to Kτ^+τ^-) < 5.4\\times10^{-4}$ at the 90\\% confidence level.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2607.25607",
  "author_total": 434,
  "authors": [
    {
      "name": "Belle"
    },
    {
      "name": "Belle II Collaborations"
    },
    {
      "name": "M. Abumusabh"
    },
    {
      "name": "I. Adachi"
    },
    {
      "name": "A. Aggarwal"
    },
    {
      "name": "Y. Ahn"
    },
    {
      "name": "H. Aihara"
    },
    {
      "name": "M. Akdag"
    },
    {
      "name": "N. Akopov"
    },
    {
      "name": "S. Alghamdi"
    },
    {
      "name": "M. Alhakami"
    },
    {
      "name": "A. Aloisio"
    },
    {
      "name": "N. Althubiti"
    },
    {
      "name": "K. Amos"
    },
    {
      "name": "M. Angelsmark"
    },
    {
      "name": "N. Anh Ky"
    },
    {
      "name": "C. Antonioli"
    },
    {
      "name": "D. M. Asner"
    },
    {
      "name": "H. Atmacan"
    },
    {
      "name": "T. Aushev"
    },
    {
      "name": "V. Aushev"
    },
    {
      "name": "R. Ayad"
    },
    {
      "name": "V. Babu"
    },
    {
      "name": "H. Bae"
    },
    {
      "name": "N. K. Baghel"
    },
    {
      "name": "S. Bahinipati"
    },
    {
      "name": "P. Bambade"
    },
    {
      "name": "Sw. Banerjee"
    },
    {
      "name": "M. Bartl"
    },
    {
      "name": "J. Baudot"
    },
    {
      "name": "A. Beaubien"
    },
    {
      "name": "F. Becherer"
    },
    {
      "name": "J. Becker"
    },
    {
      "name": "J. V. Bennett"
    },
    {
      "name": "V. Bertacchi"
    },
    {
      "name": "M. Bertemes"
    },
    {
      "name": "E. Bertholet"
    },
    {
      "name": "M. Bessner"
    },
    {
      "name": "S. Bettarini"
    },
    {
      "name": "V. Bhardwaj"
    },
    {
      "name": "B. Bhuyan"
    },
    {
      "name": "F. Bianchi"
    },
    {
      "name": "T. Bilka"
    },
    {
      "name": "D. Biswas"
    },
    {
      "name": "A. Bobrov"
    },
    {
      "name": "D. Bodrov"
    },
    {
      "name": "A. Bondar"
    },
    {
      "name": "G. Bonvicini"
    },
    {
      "name": "J. Borah"
    },
    {
      "name": "A. Boschetti"
    },
    {
      "name": "A. Bozek"
    },
    {
      "name": "M. Bračko"
    },
    {
      "name": "P. Branchini"
    },
    {
      "name": "R. A. Briere"
    },
    {
      "name": "T. E. Browder"
    },
    {
      "name": "A. Budano"
    },
    {
      "name": "S. Bussino"
    },
    {
      "name": "F. Callet"
    },
    {
      "name": "Q. Campagna"
    },
    {
      "name": "M. Campajola"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/ca8wrtqmj6bxp.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2607.25607",
  "fulltext_url": null,
  "id": "ca8wrtqmj6bxp",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2607.25607",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "hep-ex"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2607.25607",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-13",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/ca8wrtqmj6bxp.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:29:11Z",
      "native_id": "2607.25607",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2607.25607"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:hep-ex",
      "subfield": "high-energy"
    }
  ],
  "title": "Search for the $\\boldsymbol{B^0 \\to K^0_{\\rm S} τ^+ τ^-}$ decay",
  "title_text": "Search for the B^0 → K^0_S τ^+ τ^- decay",
  "type": "preprint",
  "updated_at": "2026-10-30T12:29:11Z",
  "url": "https://research.draconitic.com/paper/ca8wrtqmj6bxp",
  "venue": "arXiv",
  "versions": []
}