CMS-BPH-22-006

CMS-BPH-22-006 ; CERN-EP-2024-058
Observation of the $ {\mathrm{J}/\psi} \to\mu^{+}\mu^{-}\mu^{+}\mu^{-} $ decay in proton-proton collisions at $ \sqrt{s} = $ 13 TeV
CMS Collaboration
17 March 2024
Phys. Rev. D 109 (2024) L111101
Abstract: The $ {\mathrm{J}/\psi} \to\mu^{+}\mu^{-}\mu^{+}\mu^{-} $ 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 $ {\mathrm{J}/\psi} \to\mu^{+}\mu^{-} $ decay mode leads to a branching fraction of $ [ $ 10.1 $ ^{+3.3}_{-2.7} $ (stat) $\pm$ 0.4 (syst) $] \times$ 10$^{-7}$, a value that is consistent with the standard model prediction.
Links: e-print arXiv:2403.11352 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; HepData record ; Physics Briefing ; CADI line (restricted) ;

Figures	Summary	References	CMS Publications

Figures
png pdf	Figure 1: Leading-order Feynman diagram representing the $ {\mathrm{J}/\psi} \to\mu^{+}\mu^{-}\mu^{+}\mu^{-} $ decay channel.
png pdf	Figure 2: Measured four-muon (left) and dimuon (right) mass distributions. The vertical bars represent the statistical uncertainties. The solid black line represents the result of the unbinned fit described in the text, while the red and green lines represent the signal and background terms, respectively.
png pdf	Figure 2-a: Measured four-muon (left) and dimuon (right) mass distributions. The vertical bars represent the statistical uncertainties. The solid black line represents the result of the unbinned fit described in the text, while the red and green lines represent the signal and background terms, respectively.
png pdf	Figure 2-b: Measured four-muon (left) and dimuon (right) mass distributions. The vertical bars represent the statistical uncertainties. The solid black line represents the result of the unbinned fit described in the text, while the red and green lines represent the signal and background terms, respectively.
png pdf	Figure 2-c: Measured four-muon (left) and dimuon (right) mass distributions. The vertical bars represent the statistical uncertainties. The solid black line represents the result of the unbinned fit described in the text, while the red and green lines represent the signal and background terms, respectively.
png pdf	Figure 2-d: Measured four-muon (left) and dimuon (right) mass distributions. The vertical bars represent the statistical uncertainties. The solid black line represents the result of the unbinned fit described in the text, while the red and green lines represent the signal and background terms, respectively.

Summary

In summary, using a data sample of proton-proton collisions at $ \sqrt{s} = $ 13 TeV, collected in 2018 by the CMS Collaboration and corresponding to an integrated luminosity of 33.6 fb$ ^{-1} $, the $ {\mathrm{J}/\psi} \to\mu^{+}\mu^{-}\mu^{+}\mu^{-} $ decay was observed for the first time, with a statistical significance exceeding five standard deviations. Taking the $ {\mathrm{J}/\psi} \to\mu^{+}\mu^{-} $ decay mode as normalization, its branching fraction was measured to be $ \mathcal{B}({\mathrm{J}/\psi} \to\mu^{+}\mu^{-}\mu^{+}\mu^{-})=[ $ 10.1 $ ^{+3.3}_{-2.7} $ (stat) $ \pm $ 0.4 (syst) $ ] \times $ 10$^{-7} $, a value consistent with the standard model prediction.

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