Observation of the J/ψψ →\to μ+μ−μ+μ−μ^+μ^-μ^+μ^- decay in proton-proton collisions at s\sqrt{s} = 13 TeV

A preprint version of the article is available at arXiv:2403.11352v2 [hep-ex], https://arxiv.org/abs/2403.11352. Comments: Replaced with the published version. Added the journal reference and the DOI. All the figures and tables can be found at https://cms-results.web.cern.ch/cms-results/public-results/publications/BPH-22-006 (CMS Public Pages). Report number: CMS-BPH-22-006, CERN-EP-2024-058.The /→+⁢−⁢+⁢− decay has been observed with a statistical significance in excess of five standard deviations. The analysis is based on an event sample of proton-proton collisions at a center-of-mass energy of 13 TeV, collected by the CMS experiment in 2018 and corresponding to an integrated luminosity of 33.6  fb−1. Normalizing to the /→+⁢− decay mode leads to a branching fraction of [10.1+3.3 −2.7⁢(stat)±0.4⁢(syst)]×10−7, a value that is consistent with the standard model prediction.SCOAP3