The ALICE collaboration performed the first rapidity-differential measurement of coherent J/ψ photoproduction in ultra-peripheral Pb–Pb collisions at a center-of-mass energy sNN=5.02 TeV. The J/ψ is detected via its dimuon decay in the forward rapidity region (−4.0<−2.5) for events where the hadronic activity is required to be minimal. The analysis is based on an event sample corresponding to an integrated luminosity of about 750 μb−1. The cross section for coherent J/ψ production is presented in six rapidity bins. The results are compared with theoretical models for coherent J/ψ photoproduction. These comparisons indicate that gluon shadowing effects play a role in the photoproduction process. The ratio of ψ′ to J/ψ coherent photoproduction cross sections was measured and found to be consistent with that measured for photoproduction off protons.

Coherent J/ψ photoproduction at forward rapidity in ultra-peripheral Pb–Pb collisions at sNN=5.02 TeV / Acharya, S; Adamova, D.; Adolfson, J; Aggarwal, M.; Rinella, G.; Agnello, M.; Agrawal, N; Bufalino, S.; Concas, M.; Grosa, F.; Ravasenga, I; Fecchio, P.; Catalano, F.. - In: PHYSICS LETTERS. SECTION B. - ISSN 0370-2693. - STAMPA. - 798:134926(2019). [10.1016/j.physletb.2019.134926]

Coherent J/ψ photoproduction at forward rapidity in ultra-peripheral Pb–Pb collisions at sNN=5.02 TeV

Agnello, M.;Bufalino, S.;Concas, M.;Grosa, F.;Ravasenga, I;Fecchio, P.;Catalano, F.
2019

Abstract

The ALICE collaboration performed the first rapidity-differential measurement of coherent J/ψ photoproduction in ultra-peripheral Pb–Pb collisions at a center-of-mass energy sNN=5.02 TeV. The J/ψ is detected via its dimuon decay in the forward rapidity region (−4.0<−2.5) for events where the hadronic activity is required to be minimal. The analysis is based on an event sample corresponding to an integrated luminosity of about 750 μb−1. The cross section for coherent J/ψ production is presented in six rapidity bins. The results are compared with theoretical models for coherent J/ψ photoproduction. These comparisons indicate that gluon shadowing effects play a role in the photoproduction process. The ratio of ψ′ to J/ψ coherent photoproduction cross sections was measured and found to be consistent with that measured for photoproduction off protons.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11583/2848021