{
  "abstract": "The $12\\%$ rule relates hadronic decays of the $J/ψ$ and $ψ(2S)$ through the ratio of their wave functions at the origin, but is strongly violated in several vector--pseudoscalar ($VP$) channels, most prominently in the $ρπ$ one. We study these decays within an effective chiral framework including strong and electromagnetic interactions, with the latter implemented through vector meson dominance. The $ψ(2S)\\to VP$ data are described well by a relatively minimal model with three free parameters, yielding $χ^2_{\\rm red}\\simeq 6.71/(9-3)=1.12$. In contrast, the corresponding description of the $J/ψ$ decays is insufficient ($χ^2{\\rm _{red}}\\simeq 132/(11-3)=16.5$) and requires additional $\\mathrm{SU}(3)$ flavor breaking and electromagnetic contributions for a fair agreement with data: $χ^2_{\\rm red}\\simeq 9.87/(11-6)= 1.97$. In the past, a small mixing of $J/ψ$ with an invisible vector glueball was considered as a way to describe the decay patterns. However, we will show that our extended fits are `de facto' equivalent to those where a vector glueball mixes with the $J/ψ$, so that we cannot distinguish whether or not the vector glueball is present. Our results suggest that an important part of the $ρπ$ puzzle may arise from additional contributions to the $J/ψ\\to VP$ amplitudes rather than from a suppression mechanism specific to the $ψ(2S)$.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.24961",
  "author_total": 2,
  "authors": [
    {
      "name": "Arthur Vereijken"
    },
    {
      "name": "Francesco Giacosa"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/118wq5fb4s3cq.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.24961",
  "fulltext_url": null,
  "id": "118wq5fb4s3cq",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.24961",
  "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": "W7214025579",
  "pdf_url": "https://arxiv.org/pdf/2609.24961",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-23",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/118wq5fb4s3cq.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:23:56Z",
      "native_id": "2609.24961",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.24961"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:hep-ph",
      "subfield": "high-energy"
    }
  ],
  "title": "On the failure of the $12\\%$ rule in $J/ψ$ and $ψ(2S)$ decays",
  "title_text": "On the failure of the 12% rule in J/ψ and ψ(2S) decays",
  "type": "preprint",
  "updated_at": "2026-10-30T12:23:56Z",
  "url": "https://research.draconitic.com/paper/118wq5fb4s3cq",
  "venue": "arXiv",
  "versions": []
}