EMMI Workshop: Light-ion collisions 2026

We study charged-particle multiplicity distributions in OO, NeNe, XeXe, and PbPb collisions within the wounded-parton Glauber framework with overlayed negative binomial fluctuations, implemented in GLISSANDO. We fit directly the multiplicity distributions (histograms), simultaneously across all the systems, using the same model parameters for each reaction. The fit is performed in 1–80 % centrality range. Avoiding the most peripheral events makes the method insensitive to the normalization issues caused by the difficultly in separating the Coulomb interactions or QED cross-sections from pure hadronic cross section. The ultra-central collisions may involve different physics mechanisms. In our model, we find a universal description of multiplicity distributions across all the studied systems, except for the very central collisions, c $\lesssim$ 1%.