Quark-hadron duality in electron-nucleon scattering

Quark-hadron duality addresses some of the most fundamental issues in strong interaction physics, in particular the nature of the transition from perturbative to nonperturbative QCD. In this talk I summarize recent developments in quark-hadron duality in lepton-hadron scattering, and outline how duality can be studied at future high-luminosity facilities such as the electron-ion collider. In its broadest form, quark-hadron duality postulates that physical quantities calculated in a quark-gluon basis should be identical to those evaluated in a hadronic basis. The phenomenon of duality shows up in many physical processes, such as e+e- annihilation into hadrons, or semi-leptonic decays of heavy mesons. One of the more intriguing examples, initially observed some 30 years ago by Bloom and Gilman [1], is in inclusive inelastic electron-nucleon scattering