Measurements of quarkonium production and polarization in Pb–Pb collisions with ALICE

State Key Laboratory of Particle Detection and Electronics, University of Science and Technology of China, Hefei 230026, China

Published online: 1 March 2023

Abstract

Quarkonia are excellent probes of deconfinement in heavy-ion collisions. For J/ψ, a bound state of cc¯ quarks, the (re-)generation is found to be the dominant production mechanism at the LHC energies. Production measurements of non-prompt J/ψ, originating from beauty-hadron decays, allow one to access the interaction of beauty-quarks with the quark-gluon plasma (QGP). Polarization and spin alignment measurements can be used to investigate the characteristics of the formed medium. Moreover, it has been hypothesized that quarkonium states can be polarized by the strong magnetic field generated in the initial state of the collision and by the large angular momentum of the medium in non-central heavy-ion collisions.

In these proceedings, the measurements of the inclusive, prompt, and non-prompt J/ψ nuclear modification factor R_AA in Pb–Pb collisions at √S_NN = 5.02 TeV are shown. The measured non-prompt J/ψ fraction extends down to very low p_T with a significantly improved precision compared to previous publications. The results from the first publication on the J/ψ polarization with respect to the event-plane in Pb–Pb collisions at √S_NN = 5.02 TeV at forward rapidity are presented as well. The results are compared with available calculations.