Glauber predictions for oxygen and neon collisions at energies available at the LHC

TL;DR

This paper presents an updated version of the TGlauberMC model for simulating initial conditions in high-energy nuclear collisions, providing predictions for oxygen and neon collisions at the LHC.

Contribution

The work introduces an improved TGlauberMC (3.3) with enhanced features for small systems, including revised nuclear profiles and nucleon substructure modeling.

Findings

Predicted centrality dependence of multiplicity in OO and NeNe collisions.

Calculated geometrical cross sections for relevant collision systems.

Provided initial-state observables for particle production at 5.36 TeV.

Abstract

The Glauber model is a widely used framework for describing the initial conditions in high-energy nuclear collisions. TGlauberMC is a Monte Carlo implementation of this model that enables detailed, event-by-event calculations across various collision systems. In this work, I present an updated version of TGlauberMC (3.3), which incorporates recent theoretical developments and improved parameterizations, especially relevant for small collision systems. I focus on the oxygen-oxygen (OO), neon-neon (NeNe), and proton-oxygen (pO) collisions at the Large Hadron Collider (LHC) in July 2025, where precise modelling of nuclear geometry and fluctuations is essential. The updated version includes revised nuclear density profiles and an enhanced treatment of nucleon substructure. Geometrical cross sections for all relevant collision systems are calculated and initial-state observables are explored to provide predictions for particle production trends at $\sqrt{s_{\rm nn}}$=5.36 TeV. In particular, a prediction for the centrality dependence of mid-rapidity multiplicity in OO and NeNe collisions is obtained. The updated code is publicly available to support the heavy-ion community with a robust and flexible tool for studying strongly interacting matter in small and intermediate-sized nuclear systems.