Speaker
Description
The large data set collected by the CMS experiment during Run 3 enables studies of proton-proton collisions with unprecedented precision. Achieving comparable accuracy in simulation therefore requires a detailed understanding and careful validation of Monte Carlo (MC) event generators. In CMS, the hard-scattering process is typically simulated using generators such as MadGraph5_aMC@NLO and POWHEG, while the parton shower and non-perturbative evolution are modeled with generators such as Pythia and Herwig. These simulations rely on phenomenological descriptions of the underlying event, including multiparton interactions, color reconnection, hadronization, and other non-perturbative QCD effects, whose parameters are constrained through comparisons with data. This talk presents an overview of MC generator modelling in CMS, discussing recent jet physics measurements that probe different aspects of QCD modelling and provide constraints for the tuning and validation of event generators.