The ALICE collaboration performed the first rapidity-differential measurement of coherent J/ψ photopro- duction 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 < y < −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/$\psi$ photoproduction at forward rapidity in ultra-peripheral Pb-Pb collisions at $\sqrt{s_{\rm{NN}}}=5.02$ TeV} / ALICE collaboration, T., Acharya, S., Adamová, D., Adhya, S.P., Adler, A., Adolfsson, J., Aggarwal, M.M., Aglieri Rinella, G., Agnello, M., Agrawal, N., Ahammed, Z., Ahmad, S., Ahn, S.U., Aiola, S., Akindinov, A., Al-Turany, M., Alam, S.N., Albuquerque, D.S.D., Aleksandrov, D., Alessandro, B., et al.. - In: PHYSICS LETTERS. SECTION B. - ISSN 0370-2693. - 798:(2019). [10.1016/j.physletb.2019.134926]
{Coherent J/$\psi$ photoproduction at forward rapidity in ultra-peripheral Pb-Pb collisions at $\sqrt{s_{\rm{NN}}}=5.02$ TeV}
L. CunqueiroMembro del Collaboration Group
;N. De Marco;
2019
Abstract
The ALICE collaboration performed the first rapidity-differential measurement of coherent J/ψ photopro- duction 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 < y < −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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
