J/$ψ$ production as a function of charged-particle pseudorapidity density in p-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV

Abstract

We report measurements of the inclusive J/$ψ$ yield and average transverse momentum as a function of charged-particle pseudorapidity density ${\rm d}N_{\rm ch}/{\rm d}η$ in p-Pb collisions at $\sqrt{s_{\rm NN}}= 5.02$ 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 ${\rm d}N_{\rm ch}/{\rm d}η$, 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.

24 pages, 6 captioned figures, 4 tables, authors from page 19, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/3443