{
  "abstract": "We present a precision measurement of the branching fraction of the rare decay $J/ψ\\toμ^+μ^-μ^+μ^-$, and a search for a new gauge boson $Z^{\\prime}$ that couples only to the second and third lepton generations, using a data sample of $(8998 \\pm 39) \\times 10^6$ $J/ψ$ events collected by the BESIII detector. The branching fraction of the $J/ψ\\toμ^+μ^-μ^+μ^-$ decay is measured to be $B(J/ψ\\toμ^+μ^-μ^+μ^-)=[0.91\\pm0.04~{\\rm (stat.)}\\pm0.07~{\\rm (syst.)}]\\times 10^{-6}$, representing the most precise measurement to date and consistent with the theoretical prediction within one standard deviation. Additionally, we search for $CP$ asymmetry in the $J/ψ\\toμ^+μ^-μ^+μ^-$ decay and determine the T-odd observable to be $A_T = [0.05\\pm 0.04~{\\rm (stat.)}\\pm0.01~{\\rm (syst.)}]$, which is consistent with $CP$ conservation. In the search for $J/ψ\\to Z^{\\prime}μ^+μ^-$ via $Z^{\\prime}\\toμ^+μ^-$, no significant $Z^{\\prime}$ signal is observed in the $μ^+μ^-$ invariant mass region of $(0.212,~2.6)$~GeV$/c^2$, and we set upper limits on the ${\\rm U}(1)_{L_μ-L_τ}$ model coupling constant $g^{\\prime}$ ranging from 0.001 to 0.294 at the 90\\% confidence level, which is comparable to the upper limits set by Belle II for $Z^{\\prime}$ masses below $0.7$~GeV$/c^2$.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.37258",
  "author_total": 784,
  "authors": [
    {
      "name": "BESIII Collaboration"
    },
    {
      "name": "M. Ablikim"
    },
    {
      "name": "M. N. Achasov"
    },
    {
      "name": "P. Adlarson"
    },
    {
      "name": "X. C. Ai"
    },
    {
      "name": "C. S. Akondi"
    },
    {
      "name": "R. Aliberti"
    },
    {
      "name": "A. Amoroso"
    },
    {
      "name": "Q. An"
    },
    {
      "name": "Y. H. An"
    },
    {
      "name": "M. S. Anderson"
    },
    {
      "name": "Y. Bai"
    },
    {
      "name": "O. Bakina"
    },
    {
      "name": "H. R. Bao"
    },
    {
      "name": "X. L. Bao"
    },
    {
      "name": "M. Barbagiovanni"
    },
    {
      "name": "V. Batozskaya"
    },
    {
      "name": "K. Begzsuren"
    },
    {
      "name": "N. Berger"
    },
    {
      "name": "M. Berlowski"
    },
    {
      "name": "M. B. Bertani"
    },
    {
      "name": "D. Bettoni"
    },
    {
      "name": "F. Bianchi"
    },
    {
      "name": "E. Bianco"
    },
    {
      "name": "A. Bortone"
    },
    {
      "name": "I. Boyko"
    },
    {
      "name": "R. A. Briere"
    },
    {
      "name": "A. Brueggemann"
    },
    {
      "name": "D. Cabiati"
    },
    {
      "name": "H. Cai"
    },
    {
      "name": "M. H. Cai"
    },
    {
      "name": "X. Cai"
    },
    {
      "name": "A. Calcaterra"
    },
    {
      "name": "G. F. Cao"
    },
    {
      "name": "N. Cao"
    },
    {
      "name": "S. A. Cetin"
    },
    {
      "name": "X. Y. Chai"
    },
    {
      "name": "J. F. Chang"
    },
    {
      "name": "T. T. Chang"
    },
    {
      "name": "G. R. Che"
    },
    {
      "name": "Y. Z. Che"
    },
    {
      "name": "C. H. Chen"
    },
    {
      "name": "Chao Chen"
    },
    {
      "name": "G. Chen"
    },
    {
      "name": "H. S. Chen"
    },
    {
      "name": "H. Y. Chen"
    },
    {
      "name": "M. L. Chen"
    },
    {
      "name": "S. J. Chen"
    },
    {
      "name": "S. M. Chen"
    },
    {
      "name": "T. Chen"
    },
    {
      "name": "W. Chen"
    },
    {
      "name": "X. R. Chen"
    },
    {
      "name": "X. T. Chen"
    },
    {
      "name": "X. Y. Chen"
    },
    {
      "name": "Y. B. Chen"
    },
    {
      "name": "Y. Q. Chen"
    },
    {
      "name": "Z. K. Chen"
    },
    {
      "name": "J. Cheng"
    },
    {
      "name": "L. N. Cheng"
    },
    {
      "name": "S. K. Choi"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/a0p8df4tfb7m3.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.37258",
  "fulltext_url": null,
  "id": "a0p8df4tfb7m3",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.37258",
  "language": null,
  "licence": "CC-BY-NC-ND-4.0",
  "licence_label": "CC BY-NC-ND 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by-nc-nd/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "hep-ex"
    ],
    [
      "openalex",
      "3106|Particle physics theoretical and experimental studies"
    ]
  ],
  "openalex": "W7224111203",
  "pdf_url": "https://arxiv.org/pdf/2610.37258",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-27",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/a0p8df4tfb7m3.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:35:50Z",
      "native_id": "2610.37258",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.37258"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:hep-ex",
      "subfield": "high-energy"
    }
  ],
  "title": "Precision measurement of the $J/ψ\\toμ^+μ^-μ^+μ^-$ branching fraction and search for a new gauge boson $Z^{\\prime}$ at BESIII",
  "title_text": "Precision measurement of the J/ψ→μ^+μ^-μ^+μ^- branching fraction and search for a new gauge boson Z^′ at BESIII",
  "type": "preprint",
  "updated_at": "2026-10-30T12:35:50Z",
  "url": "https://research.draconitic.com/paper/a0p8df4tfb7m3",
  "venue": "arXiv",
  "versions": []
}