The coherent photoproduction of J / ψ and ψ ′ mesons was measured in ultra-peripheral Pb–Pb collisions at a center-of-mass energy sNN=5.02 TeV with the ALICE detector. Charmonia are detected in the central rapidity region for events where the hadronic interactions are strongly suppressed. The J / ψ is reconstructed using the dilepton (l+l-) and proton–antiproton decay channels, while for the ψ ′ the dilepton and the l+l-π+π- decay channels are studied. The analysis is based on an event sample corresponding to an integrated luminosity of about 233 μb - 1. The results are compared with theoretical models for coherent J / ψ and ψ ′ photoproduction. The coherent cross section is found to be in a good agreement with models incorporating moderate nuclear gluon shadowing of about 0.64 at a Bjorken-x of around 6 × 10 - 4, such as the EPS09 parametrization, however none of the models is able to fully describe the rapidity dependence of the coherent J / ψ cross section including ALICE measurements at forward rapidity. The ratio of ψ ′ to J / ψ coherent photoproduction cross sections was also measured and found to be consistent with the one for photoproduction off protons.

Coherent J / ψ and ψ ′ photoproduction at midrapidity in ultra-peripheral Pb–Pb collisions at √sNN=5.02 TeV / Acharya, S., Adamova, D., Adler, A., Adolfsson, J., Rinella, G.A., Agnello, M., Agrawal, N., Ahammed, Z., Ahmad, S., Ahn, S.U., Akbar, Z., Akindinov, A., Al-Turany, M., Albuquerque, D.S.D., Aleksandrov, D., Alessandro, B., Alfanda, H.M., Molina, R.A., Ali, B., Ali, Y., et al.. - In: THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS. - ISSN 1434-6044. - STAMPA. - 81:8(2021). [10.1140/epjc/s10052-021-09437-6]

Coherent J / ψ and ψ ′ photoproduction at midrapidity in ultra-peripheral Pb–Pb collisions at √sNN=5.02 TeV

Bruno G. E.;Colella D.;Fiorenza G.;
2021

Abstract

The coherent photoproduction of J / ψ and ψ ′ mesons was measured in ultra-peripheral Pb–Pb collisions at a center-of-mass energy sNN=5.02 TeV with the ALICE detector. Charmonia are detected in the central rapidity region for events where the hadronic interactions are strongly suppressed. The J / ψ is reconstructed using the dilepton (l+l-) and proton–antiproton decay channels, while for the ψ ′ the dilepton and the l+l-π+π- decay channels are studied. The analysis is based on an event sample corresponding to an integrated luminosity of about 233 μb - 1. The results are compared with theoretical models for coherent J / ψ and ψ ′ photoproduction. The coherent cross section is found to be in a good agreement with models incorporating moderate nuclear gluon shadowing of about 0.64 at a Bjorken-x of around 6 × 10 - 4, such as the EPS09 parametrization, however none of the models is able to fully describe the rapidity dependence of the coherent J / ψ cross section including ALICE measurements at forward rapidity. The ratio of ψ ′ to J / ψ coherent photoproduction cross sections was also measured and found to be consistent with the one for photoproduction off protons.
2021
Coherent J / ψ and ψ ′ photoproduction at midrapidity in ultra-peripheral Pb–Pb collisions at √sNN=5.02 TeV / Acharya, S., Adamova, D., Adler, A., Adolfsson, J., Rinella, G.A., Agnello, M., Agrawal, N., Ahammed, Z., Ahmad, S., Ahn, S.U., Akbar, Z., Akindinov, A., Al-Turany, M., Albuquerque, D.S.D., Aleksandrov, D., Alessandro, B., Alfanda, H.M., Molina, R.A., Ali, B., Ali, Y., et al.. - In: THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS. - ISSN 1434-6044. - STAMPA. - 81:8(2021). [10.1140/epjc/s10052-021-09437-6]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11589/236255
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