Ultraperipheral nuclear collisions as a source of heavy quarkonia

Heavy quarkonium production in ultraperipheral nuclear collisions (UPC) is described within the QCD
dipole formalism. Realistic quarkonium wave functions in the QQ¯ rest frame are calculated by solving the
Schrödinger equation with a subsequent Lorentz boost to high energy. We rely on several realistic QQ¯
potentials, which allow us to describe well the quarkonium masses and decay widths, as well as data on
diffractive electroproduction of quarkonia on protons. Nuclear effects are calculated with the phenomenological dipole cross sections fitted to deep-inelastic scattering (DIS) data. The higher twist quark
shadowing related to the lowest QQ¯ Fock component of the photon, as well as the leading twist gluon
shadowing, related to higher components containing gluons, are included. The results for coherent and
incoherent photoproduction of charmonia and bottomonia in UPC of heavy nuclei are in good accord with
available data from the LHC. They can also be verified in future experiments at electron-ion colliders