Diffractive vector meson photo-production in oxygen-oxygen and neon-neon ultraperipheral collisions at energies available at the CERN Large Hadron Collider
The energy-dependent hotspot model is used to predict cross sections for vector-meson diffractive photo-nuclear production off oxygen ($γ$O) and neon ($γ$Ne) that can be extracted from ultra-peripheral O--O and Ne--Ne collisions, recently recorded at the LHC. In both cases, two models are used to describe the nuclear shapes. Woods-Saxon prescriptions for O and Ne as well as an alpha-cluster description of O and a bowling-pin-like shape for Ne, according to the PGCM formalism. Predictions are presented for the dependence on the centre-of-mass energy of the photon--nucleus system, as well as on Mandelstam-$t$, of the cross sections for the coherent and the incoherent photo-nuclear production of $ρ^{0}$ and J/$ψ$ vector mesons. Furthermore, the rapidity dependence of the ultra-peripheral cross section is reported for all cases. It is found that the incoherent process provides a measurable signature for the approach to the gluon-saturation regime, and that the simultaneous determination of $ρ^{0}$ and J/$ψ$ coherent and incoherent production provides a strong constraint on nuclear models for both O and Ne.