The internal structure (substructure) of jets produced in high-energy hadron collisions encodes rich Quantum Chromodynamics (QCD) dynamics, from the interaction of quarks and gluons in the weakly coupled limit to the hadronization process in the strongly coupled limit. Studies on jet substructures have attracted interest from both the theoretical and experimental sides, together advancing our understanding of QCD. Central to the recent development of jet substructure has been the use of energy correlators, which measure statistical correlations of the energy flux within a jet. Defined as the energy-weighted cross-section of particle pairs inside jets, one unique advantage of the energy-energy correlator (EEC) over other jet substructure measurements is that they provide a calibrated probe of the scale dependence of QCD dynamics in vacuum, where the scale is controlled by the angular distance of the pairs. If one looks at the scaling behavior of the EEC as a function of pair distance, there is a perturbative regime at large angular distance and a non-perturbative (NP) regime at small angular distance. Such a distinct separation of the perturbative from the non-perturbative regime allows us to probe the dynamics of jet formation and their confinement into hadrons. In this talk, I will discuss the EEC measurements with inclusive jets in pp collisions at the LHC. From the pp measurements, the separation of the perturbative and NP region is clearly seen. Moreover, a transition region with a turn-over behavior occurs, which corresponds to the confinement process. I will also show how this observable can be used in eA collisions at the future EIC to image the scales of nuclear size and study the jet-medium interaction as a function of nuclear size.

Host: Laura Havener, Ian Moult