J/ψ yield vs. multiplicity in proton-proton collisions at the LHC

We address the question of understanding the production of J/ψ particles regarding the global underlying event in proton-proton collisions. To do so, we propose to look at a new observable: the J/ψ production as a function of the charged particles multiplicity of the event. We demonstrate the interest for an experimental measurement by varying the model of multiple interactions in the PYTHIA generator.