Hadronization

Hadronization or hadron formation is the process by which partons (quarks and gluons), which have color charge, form bound states called hadrons, which are colorless. Hadronization occurs at an energy scale $\Lambda_{QCD} \sim 500$ MeV, at which point the strong interaction is too strong to make calculations using perturbation theory. It can therefore not be calculated from first principles, but has to be described by a phenomenological model. Examples of hadronization models are the early Field-Feynman model and the more modern Lund string model as well as the cluster model.