Multiplicity Dependence of Quarkonium Production

Abstract

Recent measurements on heavy-flavour production as a function of charged-particle multiplicity at the LHC are discussed. Focus is given to quarkonium results in small (pp or pPb) collision systems. The measurements of relative yields, i.e., the ratio of the particle yields in given multiplicity intervals to the multiplicity integrated yield are presented and compared to model calculations from Monte Carlo event generators as well as to models considering effects at play in the initial and/or final state of the collision. The absolute inclusive J/ψ yield as a function of the absolute charged-particle multiplicity is evaluated; a smooth behaviour of the absolute yield is observed across collision systems, from pp to pPb and PbPb collisions. Analogous measurements of the excited-to-ground state quarkonium ratios as a function of charged-particle multiplicity are also reviewed. Finally, the study of exotic particle production as a function of charged-particle multiplicity is introduced as a complementary tool to investigate the nature of the χc1(3872) hadron.

Keywords

• heavy flavour
• quarkonium
• heavy-ion collision
• multiplicity
• multiparton interaction