Time scale of hadron formation in QCD

Determine the characteristic time scale at which colored partons produced in high-energy collisions confine into color-neutral hadrons within quantum chromodynamics (QCD), as probed by the x_L-differential two-particle (E2C) and three-particle (E3C) energy correlators inside jets.

Background

The paper measures two- and three-particle energy correlators (E2C and E3C) inside jets in proton-proton collisions. The observable x_L encodes angular separations and is related to the energy scale of interactions within the jet. The authors explain that the shape of the x_L-dependent correlators provides information about different phases of jet evolution, including a transition to non-interacting hadrons (hadron formation). They explicitly note that the time scale of hadron formation remains an open question in QCD, highlighting a fundamental unresolved aspect of strong-interaction dynamics that these correlators can inform.