EMMI Workshop: Light-ion collisions 2026

Ultra-peripheral collisions (UPCs) of light nuclei provide a unique opportunity to investigate both the spatial structure of nuclei and the dynamics of gluons at small Bjorken-$x$. In this contribution, I will present predictions for exclusive $\mathrm{J}/\psi$ photoproduction in oxygen-oxygen and neon-neon UPCs within an impact-parameter-dependent Color Glass Condensate framework...

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...

Starting from the momentum-space dilute-dilute computation of single-inclusive gluon production in the CGC framework [1,2], where the leading-order cross section is written as convolution of two unintegrated gluon distributions through the Lipatov vertex, I show that this result is just the zeroth order of a gradient expansion in the transverse positions entering the two dipole amplitudes....

In large collision systems, the initial elliptical geometry generated at finite impact parameter gives rise to the elliptic flow coefficient $v_2$, whose centrality dependence is largely determined by this geometry. In contrast, intermediate and small systems exhibit a much weaker centrality dependence. To investigate the origin of $v_2$ in oxygen-oxygen collisions, we decompose the...