2022/10/09 by Paul, Biswarup
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #Nuclear Experiment (nucl-ex)
paper · doi:10.48550/arxiv.2210.04353
Charmonium production is a probe sensitive to deconfinement in nucleus--nucleus collisions. The production of J/ψ via regeneration within the QGP or at the phase boundary has been identified as an important ingredient for the description of the observed centrality and p\rm T dependence at the LHC. ψ(2S) production relative to J/ψ is one possible discriminator between the two different regeneration scenarios. At RHIC and at the LHC, there is so far no significant observation of the ψ(2S) in nucleus--nucleus collisions in central events at low transverse momentum, where regeneration is the dominating process. The combined Run 2 data set of ALICE allows to extract a significant ψ(2S) signal in such a kinematic region at forward rapidity in the dimuon decay channel. In this contribution, we present for the first time results on the ψ(2S)-to-J/ψ double ratio and the ψ(2S) nuclear modification factor in Pb--Pb collisions at √s\rm NN = 5.02 TeV, calculated with respect to a new pp reference with improved precision. Results are compared with model calculations.