EMMI Workshop: Light-ion collisions 2026

The recent light-ion collision programme at RHIC and the LHC provides a unique opportunity to investigate the onset of quark-gluon plasma formation and parton energy loss in small systems. A quantitative interpretation of emerging jet-quenching measurements requires precise control over cold nuclear matter (CNM) effects, which modify hard-process cross sections independently of any hot-medium dynamics.
This talk, based on [1], gives an overview of pQCD baseline predictions for hadron and electroweak‑boson production in p–O, O–O and Ne–Ne collisions at the LHC, using a comprehensive set of nuclear PDFs. Furthermore, a set of multi‑cross‑section ratios is presented in which CNM effects and their uncertainties largely cancel, resulting in observables that are particularly well‑suited to isolating genuine energy‑loss signals.

[1] F. Jonas, C. Loizides, A. Mazeliauskas, P. Paakkinen and N. Strangmann, A compendium of cold-nuclear matter baseline predictions in light-ion collisions, arXiv:2602.15928 hep-ph (accepted by EPJC)