Unraveling the final-state interactions and correlations inside high-multiplicity jets at LHC

Recent CMS measurements on high-multiplicity jets have revealed intriguing near-side long-range correlations in two-particle correlations within jets containing over 80 charged tracks. These structures suggest the potential existence of final-state interactions beyond those considered in current parton shower programs. In this study, we investigate three mechanisms that may become significant when the phase-space density of particles becomes high: twoto- two partonic rescattering, two-to-one partonic fusion, and hadronic rescattering. These processes are implemented at the end of the PYTHIA8 parton shower. We pay particular attention to modeling the spacetime evolution of partons and tracking the color flow during their interactions. Our analysis explores how these effects influence particle correlations in high-multiplicity jet events, offering insights into the underlying dynamics and providing potential directions for improving theoretical models in this regime.