/ nucl-ex CERN-EP-2017-056

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

Pages: 24

Abstract: We report measurements of the inclusive J/$\psi$ yield and average transverse momentum as a function of charged-particle pseudorapidity density ${\rm d}N_{\rm ch}/{\rm d}\eta$ 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/$\psi$ yield with normalised ${\rm d}N_{\rm ch}/{\rm d}\eta$ is observed at mid-rapidity and backward rapidity, similar to that found earlier in pp collisions. 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 rapidity 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/$\psi$ production at forward rapidity with respect to backward rapidity for increasing charged-particle multiplicity.

Note: 24 pages, 6 captioned figures, 4 tables, authors from page 19, submitted to PLB, figures at http://aliceinfo.cern.ch/ArtSubmission/node/3443

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