Overview of ALICE results on ultra-peripheral collisions

Abstract

Lead nuclei, accelerated at the LHC, are sources of strong electromagnetic fields which can be used to measure photon-induced interactions in a new kinematic regime. These interactions can be studied in ultra-peripheral p–Pb and Pb–Pb collisions where impact parameters are larger than the sum of nuclear radii and hadronic interactions are strongly suppressed. Heavy quarkonium photoproduction is of particular interest since it is sensitive to gluon distributions in target hadrons. An overview of ALICE results on vector meson photoproduction in ultra-peripheral Pb–Pb and p–Pb collisions will be presented. Implications to study gluon density distributions and nuclear gluon shadowing will be discussed.