Ground and excited quarkonium states as probes of MPI in small systems with ALICE

TL;DR

This paper discusses how quarkonium states can be used to probe multiparton interactions in small collision systems, presenting new measurements from ALICE on quarkonium yields and ratios as functions of multiplicity, and comparing them with theoretical models.

Contribution

The paper provides new experimental results on quarkonium production and ratios in small systems, enhancing understanding of MPI effects and testing theoretical predictions.

Findings

Self-normalized charmonium yields increase with multiplicity.

Excited-to-ground state charmonium ratios vary with multiplicity.

Double J/ψ production measurements at 13 TeV are reported.

Abstract

Quarkonia represent excellent tools for understanding the role of multiparton interactions (MPI) in small systems, i.e., pp and p-A collisions. Probing MPI with quarkonia can be done directly by looking at quarkonium associated production, or indirectly by studying the multiplicity dependence of quarkonium production. In these proceedings, the results from the ALICE experiment on direct and indirect MPI probes are discussed. The self-normalized yields of charmonium production as a function of the charged-particle multiplicity in pp and p--Pb collisions at \sqrt{s} = 13 TeV and \sqrt{s_{NN} = 8.16 TeV, respectively, are discussed. Additionally, the corresponding measurements of the charmonium self-normalized excited-to-ground state ratio as a function of the charged-particle multiplicity are reported. The new measurement of the double J/\psi production at forward rapidity in pp collisions at \sqrt{s} = 13 TeV TeV is presented. Finally, the multiplicity dependence of the bottomonium production in pp collisions at \sqrt{s} = 13 TeV is discussed. The comparison to the available theoretical calculations is reported.