{
  "abstract": "We present a study of the three-body, singly Cabibbo-suppressed decays $Λ_c^+ \\to ΛK^+ π^0$ and $Λ_c^+ \\to ΛK^+ η$ using data recorded with the Belle and Belle II detectors at the KEKB and SuperKEKB $e^+ e^-$ colliders. The data samples correspond to integrated luminosities of 980$\\,\\mathrm{fb}^{-1}$ and 570$\\,\\mathrm{fb}^{-1}$, respectively. We measure their branching-fraction ratios relative to the Cabibbo-favored decay $Λ_c^+ \\to Λπ^+ π^0$ as $\\mathcal{B}(Λ_c^+ \\to ΛK^+ π^0)/\\mathcal{B}(Λ_c^+ \\to Λπ^+ π^0)=(1.82 \\pm 0.07 \\pm 0.07)\\%$, with significantly improved precision compared to the previous measurement, and $\\mathcal{B}(Λ_c^+ \\to ΛK^+ η)/\\mathcal{B}(Λ_c^+ \\to Λπ^+ π^0)=(8.73 \\pm 0.35 \\pm 0.43)\\times10^{-3}$, corresponding to the first observation of the $Λ_c^+ \\to ΛK^+ η$ decay with a statistical significance exceeding 10 standard deviations. The first and second uncertainties are statistical and systematic, respectively. Using the world-average value of the branching fraction for $Λ_c^+ \\to Λπ^+ π^0$, we obtain the branching fractions $\\mathcal{B}(Λ_c^+ \\to ΛK^+ π^0)=(1.29\\pm 0.05\\pm 0.05\\pm 0.06)\\times10^{-3}$ and $\\mathcal{B}(Λ_c^+ \\to ΛK^+ η)=(6.20\\pm 0.25\\pm 0.31\\pm 0.30)\\times10^{-4}$, where the third uncertainty arises from the uncertainty in the world-average value of $\\mathcal{B}(Λ_c^+ \\to Λπ^+ π^0)$. The measured $\\mathcal{B}(Λ_c^+\\toΛK^+η)$ is significantly larger than predictions based on $SU(3)$ flavor symmetry.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.31377",
  "author_total": 403,
  "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": "A. Akram"
    },
    {
      "name": "S. Alghamdi"
    },
    {
      "name": "M. Alhakami"
    },
    {
      "name": "A. Aloisio"
    },
    {
      "name": "N. Althubiti"
    },
    {
      "name": "K. Amos"
    },
    {
      "name": "M. Angelsmark"
    },
    {
      "name": "N. Anh Ky"
    },
    {
      "name": "K. Arai"
    },
    {
      "name": "H. Atmacan"
    },
    {
      "name": "T. Aushev"
    },
    {
      "name": "V. Aushev"
    },
    {
      "name": "R. Ayad"
    },
    {
      "name": "V. Babu"
    },
    {
      "name": "N. K. Baghel"
    },
    {
      "name": "S. Bahinipati"
    },
    {
      "name": "P. Bambade"
    },
    {
      "name": "Sw. Banerjee"
    },
    {
      "name": "M. Barrett"
    },
    {
      "name": "M. Bartl"
    },
    {
      "name": "J. Baudot"
    },
    {
      "name": "A. Beaubien"
    },
    {
      "name": "F. Becherer"
    },
    {
      "name": "J. Becker"
    },
    {
      "name": "G. F. Benfratello"
    },
    {
      "name": "J. V. Bennett"
    },
    {
      "name": "V. Bertacchi"
    },
    {
      "name": "M. Bertemes"
    },
    {
      "name": "E. Bertholet"
    },
    {
      "name": "M. Bessner"
    },
    {
      "name": "S. Bettarini"
    },
    {
      "name": "P. Bhagawath Prasad"
    },
    {
      "name": "V. Bhardwaj"
    },
    {
      "name": "B. Bhuyan"
    },
    {
      "name": "F. Bianchi"
    },
    {
      "name": "T. Bilka"
    },
    {
      "name": "A. Biswas"
    },
    {
      "name": "A. Bobrov"
    },
    {
      "name": "A. Bondar"
    },
    {
      "name": "G. Bonvicini"
    },
    {
      "name": "A. Boschetti"
    },
    {
      "name": "A. Bozek"
    },
    {
      "name": "M. Bračko"
    },
    {
      "name": "P. Branchini"
    },
    {
      "name": "N. Brenny"
    },
    {
      "name": "R. A. Briere"
    },
    {
      "name": "T. E. Browder"
    },
    {
      "name": "A. Budano"
    },
    {
      "name": "F. Callet"
    },
    {
      "name": "Q. Campagna"
    },
    {
      "name": "M. Campajola"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/7kvmyrmycbpts.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.31377",
  "fulltext_url": null,
  "id": "7kvmyrmycbpts",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.31377",
  "language": null,
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "hep-ex"
    ],
    [
      "openalex",
      "3106|Particle physics theoretical and experimental studies"
    ]
  ],
  "openalex": "W7223400435",
  "pdf_url": "https://arxiv.org/pdf/2610.31377",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-22",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/7kvmyrmycbpts.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:34:34Z",
      "native_id": "2610.31377",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.31377"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:hep-ex",
      "subfield": "high-energy"
    }
  ],
  "title": "Measurements of the branching fractions of $Λ_c^+\\toΛK^+ π^0$ and $Λ_c^+\\toΛK^+ η$ decays at Belle and Belle II",
  "title_text": "Measurements of the branching fractions of Λ_c^+→ΛK^+ π^0 and Λ_c^+→ΛK^+ η decays at Belle and Belle II",
  "type": "preprint",
  "updated_at": "2026-10-30T12:34:34Z",
  "url": "https://research.draconitic.com/paper/7kvmyrmycbpts",
  "venue": "arXiv",
  "versions": []
}