Precision measurement of the $J/ψ\toμ^+μ^-μ^+μ^-$ branching fraction and search for a new gauge boson $Z^{\prime}$ at BESIII
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$/c^2$.
Authors
- S. M. Chen (ORCID: https://orcid.org/0009-0001-9273-6140)
- K. Begzsuren
- Niklaus Berger (ORCID: https://orcid.org/0000-0002-9659-8507)
- V. Batozskaya (ORCID: https://orcid.org/0000-0003-1089-9200)
- A. Calcaterra
- G. F. Cao (ORCID: https://orcid.org/0000-0001-9135-3888)
- S. S. Fang (ORCID: https://orcid.org/0000-0002-5247-3833)
- D. Bettoni (ORCID: https://orcid.org/0000-0002-4158-6496)
- Igor R. Boyko (ORCID: https://orcid.org/0000-0002-3355-4662)
- H. L. Dai (ORCID: https://orcid.org/0000-0002-1405-1330)
- Z. H. Duan (ORCID: https://orcid.org/0009-0002-2501-9851)
- S. J. Chen (ORCID: https://orcid.org/0000-0002-2376-8413)
- G Cibinetto
- S. K. Choi
- E. Bianco
- C. Q. Deng (ORCID: https://orcid.org/0009-0004-6810-2836)
- M. L. Chen (ORCID: https://orcid.org/0000-0003-0447-5348)
- A. Brueggemann (ORCID: https://orcid.org/0009-0006-5224-894X)
- Roy A. Briere (ORCID: https://orcid.org/0000-0001-5229-1039)
- G. R. Che (ORCID: https://orcid.org/0009-0008-4382-8736)
- A. Bortone (ORCID: https://orcid.org/0000-0003-1577-5004)
- X. Y. Chai (ORCID: https://orcid.org/0000-0003-1919-360X)
- E. Di Fiore (ORCID: https://orcid.org/0009-0003-1978-9072)
- X. C. Ai (ORCID: https://orcid.org/0000-0003-3856-2415)
- Fabrizio Bianchi (ORCID: https://orcid.org/0000-0002-1524-6236)
- A. G. Denig (ORCID: https://orcid.org/0000-0001-7974-5854)
- D. Dedovich
- M Destefanis
- BESIII Collaboration
- H. -R. Bao (ORCID: https://orcid.org/0009-0002-7027-021X)
- Y. Z. Che (ORCID: https://orcid.org/0009-0008-8029-3240)
- R. Aliberti (ORCID: https://orcid.org/0000-0003-3500-4012)
- M. Y. Dong (ORCID: https://orcid.org/0009-0004-3851-2674)
- F. De Mori (ORCID: https://orcid.org/0000-0002-3951-272X)
- M. N. Achasov
- M. Berlowski
- M. C. Du (ORCID: https://orcid.org/0009-0002-4693-5429)
- S. X. Du (ORCID: https://orcid.org/0009-0002-5682-0414)
- T. T. Chang (ORCID: https://orcid.org/0009-0000-8361-147X)
- J. Cottee-Meldrum
- S Gevrek Çetin
- R. E. de Boer
- F. Cossio
- H. S. Chen (ORCID: https://orcid.org/0009-0009-2165-7910)
- A. Amoroso (ORCID: https://orcid.org/0000-0002-3095-8610)
- K. X. Fan (ORCID: https://orcid.org/0009-0009-4437-3742)
- P Adlarson (ORCID: https://orcid.org/0000-0001-6280-3851)
- M. Ablikim (ORCID: https://orcid.org/0000-0002-3935-619X)
- M. H. Cai (ORCID: https://orcid.org/0000-0003-2244-0392)
- M. Barbagiovanni (ORCID: https://orcid.org/0009-0009-5356-3169)
- D. Cabiati (ORCID: https://orcid.org/0009-0004-3608-7969)
- M. B. Bertani
- M. S. Anderson (ORCID: https://orcid.org/0009-0008-1550-2632)
- C. S. Akondi
- X. L. Bao (ORCID: https://orcid.org/0009-0000-3355-8359)
- G. F. Fan (ORCID: https://orcid.org/0009-0008-5248-9748)
- P. Egorov
- A. Dbeyssi
- O. Bakina
- I. Denisenko
- Z. Y. Deng
- L. Y. Dong
- X. L. Du
- Z. K. Chen
- Y. Q. Chen
- Jin Fang
- J. J. Fan
- H. Cai
- J. Fang
- J. P. Dai
- J. Cheng
- W. Chen
- L. N. Cheng
- J. F. Chang
- Y. Bai
- G. Chen
- X. Chu
- Y. Q. Du
- Y. H. Fan
- X. K. Cai
- X. Dong
- C. H. Chen
- H. Y. Chen
- T. Chen
- Y. H. An
- N. Cao
- X. X. Ding
- Y. X. Ding
- Z. J. Dong
- X. C. Dai
- Chao Chen
- X. Y. Chen
- Shaoxu Du
- J. Dong
- Q. An
- Y. Y. Duan
Publication Details
- Journal
- arXiv (Cornell University)
- Published
- 2026-10-27
- DOI
- https://doi.org/10.48550/arxiv.2610.37258
- Primary Topic
- Particle physics theoretical and experimental studies
- Type
- preprint