Speaker
Description
The analysis of J/$\psi$ photoproduction in ultra-peripheral collisions
(UPC) of heavy ions allows for perturbative QCD considerations which
address the gluon saturation and nuclear shadowing. J/$\psi$ and $\psi^{'}$
photoproduction cross sections in Pb--Pb UPC, measured by ALICE both at forward
and central rapidities, are compared with available QCD-based models.
The first measurement of the cross section for coherent J/$\psi$ production
in Pb--Pb UPC as a function of |t| provides a tool to constrain
the transverse gluonic structure in nuclei at very low Bjorken-$x$.
Preliminary results on J/$\psi$ photoproduction and exclusive dimuon
production in p--Pb UPC are presented.
The light-meson photonuclear production in UPC at the LHC
approaches the black-disk limit of QCD. The cross sections of the
$\rho^{0}$ coherent photoproduction in Pb--Pb and Xe--Xe UPC were
measured for different nuclear-breakup classes. The results are
compared with model predictions.
