Speakers
Description
The availability of the largest collision energy in pp collisions at the LHC allows a significant advance in the measurement of J/$\psi$ production as a function of event multiplicity. The interesting relative increase measured in pp collisions at the LHC at $\sqrt{s} = 7$ TeV and at RHIC at $\sqrt{s} = 200$ GeV is studied now at unprecedented multiplicities for pp collisions. The newest measurement performed at mid-rapidity in pp collisions at $\sqrt{s} = 13$ TeV, facilitated by triggering on high-multiplicity events, imposes strong constraints to theoretical models, such as those implementing multiple partonic interactions. Also, it allows the comparison with the J/$\psi$ production studied in p-Pb collisions at similar event multiplicities. We will show our newest measurements of J/$\psi$ yields as a function of transverse momentum and event multiplicity in pp collisions at $\sqrt{s} =$ 2.76, 5.02 and 13 TeV at mid- and forward-rapidity together with those obtained in p-Pb collisions at $\sqrt{s_{\rm NN}} =$ 5.02 and 8.16 TeV.The discussion will include comparisons with recent theoretical calculations.
