Sprecher
Beschreibung
Charmonium production is a probe sensitive to deconfinement in nucleus-nucleus collisions. The production of J/$\psi$ via regeneration within the QGP or at the phase boundary has been identified as an important ingredient for the description of the observed J/$\psi$ nuclear modification factor at the LHC. The $\psi$(2S) production relative to J/$\psi$ is a possible discriminator between the two different scenarios. Studies of $\psi$(2S) production in central nucleus-nucleus collisions at low transverse momentum ($p_{\rm T}$) are crucial, in particular at the LHC, where regeneration might be dominant. For the first time, a significant $\psi$(2S) signal is extracted in such a kinematic region at forward rapidity in the dimuon decay channel. This measurement relies on the recently published $\psi$(2S) cross section measured in pp collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV with an unprecedent precision compared to previous ALICE results.
In this contribution, we present newly published results on the $\psi$(2S)-to-J/$\psi$ (double) ratio and the $\psi$(2S) nuclear modification factor in Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV. Results are reported as a function of centrality and $p_{\rm T}$ in the region $p_{\rm T} < $ 12 GeV/c and are compared to available NA50 and CMS measurements. Comparisons to transport and statistical hadronization model predictions are also provided to shed light on charmonium states recombination mechanism.
Affiliation
ALICE
| Experiment/Theory | ALICE |
|---|