Speakers
Description
The electromagnetic fields of lead nuclei at the LHC are an intense source of quasi-real photons. The coherent photonuclear production of J/$\psi$ provides information about the intial state of nuclei at a perturbative scale related to the mass of the charm quark. Using data from Run 1 at the LHC, the ALICE Collaboration has published cross section measurements of coherent photoproduction of J/$\psi$ in peripheral (with nuclear overlap) and ultra-peripheral (without nuclear overlap) Pb-Pb collisions. Coherent photoproduction is characterized by very low $p_{\rm T}$ of the produced J/$\psi$ ($p_{\rm T} \sim 1/R = 30$ MeV/$c$), and in this region of phase space photoproduction dominates over hadroproduction in collisions down to at least 50% centrality. These results will be reviewed here. In addition, new results from Run 2 data for peripheral collisions at mid rapidity, as well as for ultra-peripheral collisions at forward rapidities will be presented.
