Observation of the ϒ⁡(3⁢𝑆) Meson and Suppression of ϒ States in Pb-Pb Collisions at √𝑠𝑁⁢𝑁=5.02 TeV

Abstract

The production of ϒ⁡(2⁢𝑆) and ϒ⁡(3⁢𝑆) mesons in lead-lead (Pb-Pb) and proton-proton (𝑝⁢𝑝) collisions is studied in their dimuon decay channel using the CMS detector at the LHC. The ϒ⁡(3⁢𝑆) 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 𝑝⁢𝑝 collisions are reported for both the ϒ⁡(2⁢𝑆) and ϒ⁡(3⁢𝑆) 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 ϒ yields in Pb-Pb collisions. This suppression increases from peripheral to central Pb-Pb collisions. Furthermore, the suppression is stronger for ϒ⁡(3⁢𝑆) mesons compared to ϒ⁡(2⁢𝑆) mesons, extending the pattern of sequential suppression of quarkonium states in nuclear collisions previously seen for the 𝐽/𝜓, 𝜓⁡(2⁢𝑆), ϒ⁡(1⁢𝑆), and ϒ⁡(2⁢𝑆) mesons.