J/ψ and ψ(2S) production at forward rapidity in p+p collisions at s=510 GeV
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The first observation of the decay and measurement of the branching ratio of to are presented. The and mesons are reconstructed using their dimuon decay modes. The results are based on proton-proton colliding beam data from the LHC collected by the CMS experiment at in 2016–2018, corresponding to an integrated luminosity of . The branching fraction ratio is measured to be , where the last uncertainty comes from the uncertainties in the branching fractions of the charmonium states. New measurements of the baryon mass and natural width are also presented, using the final state, where the baryon is reconstructed through the decays , , , and . Finally, the fraction of baryons produced from decays is determined. © 2024 CERN, for the CMS Collaboration2024CERNmore » « less
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The production of and mesons in lead-lead (Pb-Pb) and proton-proton ( ) collisions is studied in their dimuon decay channel using the CMS detector at the LHC. The meson is observed for the first time in Pb-Pb collisions, with a significance above 5 standard deviations. The ratios of yields measured in Pb-Pb and collisions are reported for both the and mesons, as functions of transverse momentum and Pb-Pb collision centrality. These ratios, when appropriately scaled, are significantly less than unity, indicating a suppression of yields in Pb-Pb collisions. This suppression increases from peripheral to central Pb-Pb collisions. Furthermore, the suppression is stronger for mesons compared to mesons, extending the pattern of sequential suppression of quarkonium states in nuclear collisions previously seen for the , , , and mesons. © 2024 CERN, for the CMS Collaboration2024CERNmore » « less