The production of Upsilon(2S) and Upsilon(3S) mesons in lead-lead (Pb-Pb) and proton-proton (pp) collisions is studied in their dimuon decay channel using the CMS detector at the LHC. The Upsilon(3S) 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 pp collisions are reported for both the Upsilon(2S) and Upsilon(3S) 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 Upsilon yields in Pb-Pb collisions. This suppression increases from peripheral to central Pb-Pb collisions. Furthermore, the suppression is stronger for Upsilon(3S) mesons compared to Upsilon(2S) mesons, extending the pattern of sequential suppression of quarkonium states in nuclear collisions previously seen for the J/psi, psi(2S), Upsilon(1S), and Upsilon(2S) mesons.
Observation of the ϒ(3S) Meson and Suppression of ϒ States in Pb-Pb Collisions at sNN=5.02 TeV
Calligaris, L.;Aimè, C.;Asenov, P.;Bianchini, L.;Bossini, E.;Bruschini, D.;Ciocci, M. A.;Donato, S.;Messineo, A.;Musich, M.;Rizzi, A.;Cipriani, M.;Marini, A. C.;
2024-01-01
Abstract
The production of Upsilon(2S) and Upsilon(3S) mesons in lead-lead (Pb-Pb) and proton-proton (pp) collisions is studied in their dimuon decay channel using the CMS detector at the LHC. The Upsilon(3S) 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 pp collisions are reported for both the Upsilon(2S) and Upsilon(3S) 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 Upsilon yields in Pb-Pb collisions. This suppression increases from peripheral to central Pb-Pb collisions. Furthermore, the suppression is stronger for Upsilon(3S) mesons compared to Upsilon(2S) mesons, extending the pattern of sequential suppression of quarkonium states in nuclear collisions previously seen for the J/psi, psi(2S), Upsilon(1S), and Upsilon(2S) mesons.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.