Suppression of ψ(2S) production in p-Pb collisions at sNN$$ \sqrt{s_{\mathrm{NN}}} $$ = 5.02 TeV

By B. Abelev, L. Hanratty, M. Esposito, E. Garcia-Solis, R. Majka, M. Bregant, M. Marchisone, P. Vyvre, C. Petta, M. Planinić and 938 more. 2014

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A bstractThe ALICE Collaboration has studied the inclusive production of the charmonium state ψ(2S) in proton-lead (p-Pb) collisions at the nucleon-nucleon centre of mass energy sNN$$ \sqrt{s_{\mathrm{NN}}} $$ = 5.02 TeV at the CERN LHC. The measurement was performed at forward (2.03 < ycms< 3.53) and backward (−4.46 < ycms< −2.96) centre of mass rapidities, studying the decays into muon pairs. In this paper, we present the inclusive production cross sections σψ(2S), both integrated and as a function of the transverse momentum pT, for the two ycms domains. The results are compared to those obtained for the 1S vector state (J/ψ), by showing the ratios between the production cross sections, as well as the double ratios [σψ(2S)/σJ/ψ ]pPb/[σψ(2S)/σJ/ψ]pp between p-Pb and proton-proton collisions. Finally, the nuclear modification factor for inclusive ψ(2S) is evaluated and compared to the measurement of the same quantity for J/ψ and to theoretical models including parton shadowing and coherent energy loss mechanisms. The results show a significantly larger suppression of the ψ(2S) compared to that measured for J/ψ and to models. These observations represent a clear indication for sizeable final state effects on ψ(2S) production.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/f1d31e6101b3dbaf1396a62bb5657453f8c9b2c3