Jets: In-medium parton evolution with finite size effects

This proceeding presents a personal perspective on the status of jetquenching in small collision systems, based on a plenary talk delivered at the 12th International Conference on Hard and Electromagnetic Probes of High- Energy Nuclear Collisions. Theoretical models of partonic energy loss, developed primarily for large, equilibrated systems, face significant challenges when applied to small systems where the assumptions of scale separation and medium uniformity no longer hold. Inclusive observables such as R AA and high- p T v 2 are shown to have limited resolving power in these regimes, and efforts to fit both consistently remain highly sensitive to modeling choices, including the treatment of early-time energy loss and hadronization mechanisms. This talk argues that small systems are not discovery environments, but rather precision calibration tools that can expose theoretical ambiguities and guide the development of more refined, space-time-sensitive observables. In particular, recent advances in jet substructure and formation-time-based techniques offer a promising route to disentangle when and where energy loss occurs, with potentially greater interpretability in small systems than traditional observables.