{
  "abstract": "Triangle singularities, predicted by Landau in 1959, are purely kinematic enhancements arising from hadronic rescattering loops. Despite their proposed role in various anomalous decay processes and exotic hadron candidates, a direct experimental confirmation has remained elusive for more than six decades. We analyze the $pη/\\bar{p}η$ invariant mass spectrum in $ψ(2S) \\to p\\bar{p}η$ measured by the BESIII Collaboration. The data exhibit a clear cusp-like structure around 1.564~GeV in the $N(1535)$ region, in precise agreement with the kinematic position predicted for the triangle singularity. Including the triangle singularity loop in the fit substantially improves the description of the data, with $χ^2/\\mathrm{d.o.f.}$ decreasing from 1.22 to 0.90, corresponding to a significance of $\\sim 3.8σ$ for the triangle singularity contribution. The precise alignment of the observed excess with the predicted kinematic position provides the first compelling evidence for the triangle singularity effect.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2608.29006",
  "author_total": 5,
  "authors": [
    {
      "name": "Qi Huang"
    },
    {
      "name": "Yi-Jia Zeng"
    },
    {
      "name": "Xiao-Rui Lyu"
    },
    {
      "name": "Rong-Gang Ping"
    },
    {
      "name": "Jia-Jun Wu"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/f4mdp4ph86bss.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2608.29006",
  "fulltext_url": null,
  "id": "f4mdp4ph86bss",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2608.29006",
  "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-ph"
    ],
    [
      "openalex",
      "3106|Quantum Chromodynamics and Particle Interactions"
    ]
  ],
  "openalex": "W7204891463",
  "pdf_url": "https://arxiv.org/pdf/2608.29006",
  "pmcid": null,
  "pmid": null,
  "published": "2026-08-29",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/f4mdp4ph86bss.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:41Z",
      "native_id": "2608.29006",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2608.29006"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:hep-ph",
      "subfield": "high-energy"
    }
  ],
  "title": "First Evidence for an Unambiguous Triangle Singularity from $ψ(2S) \\to p\\bar{p}η$",
  "title_text": "First Evidence for an Unambiguous Triangle Singularity from ψ(2S) → pp̅η",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:41Z",
  "url": "https://research.draconitic.com/paper/f4mdp4ph86bss",
  "venue": "arXiv",
  "versions": []
}