J/ ψ production as a function of charged-particle pseudorapidity density in p–Pb collisions at s NN = 5.02 TeV

摘要

We report measurements of the inclusive J/ ψ yield and average transverse momentum as a function of charged-particle pseudorapidity density d N ch / d η in p–Pb collisions at s NN = 5.02 TeV with ALICE at the LHC. The observables are normalised to their corresponding averages in non-single diffractive events. An increase of the normalised J/ ψ yield with normalised d N ch / d η , measured at mid-rapidity, is observed at mid-rapidity and backward rapidity. At forward rapidity, a saturation of the relative yield is observed for high charged-particle multiplicities. The normalised average transverse momentum at forward and backward rapidities increases with multiplicity at low multiplicities and saturates beyond moderate multiplicities. In addition, the forward-to-backward nuclear modification factor ratio is also reported, showing an increasing suppression of J/ ψ production at forward rapidity with respect to backward rapidity for increasing charged-particle multiplicity.