Coherent J/ψ photoproduction in peripheral heavy-ion collisions

In 2015, the ALICE Collaboration reported the first measurement of an excess in the yield of J/psi at very low transverse momentum (p(T) < 0.3GeV/c) in the forward rapidity region (2.5 < y < 4) in peripheral lead-lead (Pb-Pb) collisions at root s(NN) = 2.76 TeV at the CERN LHC. The coherent photoproduction was proposed as the potential underlying physics mechanism. This is known to be the main production mechanism for low-p(T) J/psi production in ultra-peripheral collisions, which are dominated by electromagnetic interactions. However, the observation of a large effect in more central collisions that are dominated by the hadronic interactions was quite surprising. This article represents a proceeding contribution on the preliminary results from Pb-Pb collisions at root s(NN) = 5.02 TeV shown in a poster during the National Congress of the French Physical Society in July 2019. Copyright CERN for the benefit of the ALICE Collaboration. Published by the EPLA under the terms of the Creative Commons Attribution 3.0 License (CC BY).