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Title: Centrality dependence of proton and antiproton spectra in Pb + Pb collisions at 40A GeV and 158A GeV measured at the CERN Super Proton Synchrotron
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  1. The production of theψ(2S)charmonium state was measured with ALICE in Pb-Pb collisions atsNN=5.02TeV, in the dimuon decay channel. A significant signal was observed for the first time at LHC energies down to zero transverse momentum, at forward rapidity (2.5<y<4). The measurement of the ratio of the inclusive production cross sections of theψ(2S)andJ/ψresonances is reported as a function of the centrality of the collisions and of transverse momentum, in the regionpT<12GeV/c. The results are compared with the corresponding measurements inppcollisions, by forming the double ratio[σψ(2S)/σJ/ψ]PbPb/[σψ(2S)/σJ/ψ]pp. It is found that in Pb-Pb collisions theψ(2S)is suppressed by a factor of2with respect to theJ/ψ. Theψ(2S)nuclear modification factorRAAwas also obtained as a function of both centrality andpT. The results show that theψ(2S)resonance yield is strongly suppressed in Pb-Pb collisions, by a factor of up to3with respect topp. Comparisons of cross section ratios with previous Super Proton Synchrotron findings by the NA50 experiment and ofRAAwith higher-pTresults at LHC energy are also reported. These results and the corresponding comparisons with calculations of transport and statistical models address questions on the presence and properties of charmonium states in the quark-gluon plasma formed in nuclear collisions at the LHC.

    © 2024 CERN, for the ALICE Collaboration2024CERN 
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