EMMI Workshop: Light-ion collisions 2026

In ultra-pheripheral photonuclear interactions, a vector meson (VM) can be produced if the photon from the emitting ion interacts with gluons in the target ion. Such processes are sensitive to the nuclear structure, including modifications to the nuclear parton distribution functions and the geometrical shape of the nuclei. Coherent and incoherent VM photoproduction (where either the whole nucleus or a single nucleon acts as a target) in high-energy collisions allow us to probe the nuclear structure at low values of Bjorken-x, where saturation and shadowing effects are expected to become important. On the other hand, VM photoproduction in fixed target mode with SMOG2 at LHCb, provides access to higher Bjorken-x at different kinematics. We perform a phenomenological study with the STARLIGHT Monte Carlo generator, assessing the expected experimental precision at LHCb and ALICE on the cross sections of coherent and incoherent VM photoproduction in light ion Run 3 data. The discriminating power between these contributions is investigated, in order to learn whether such measurements will be able to differentiate between various models for nuclear structure. Additionally, I discuss possible extensions of VM photoproduction measurements to new species of colliding ions at the LHC Run 4 and implications for theoretical nuclear physics.