Quark-Hadron Duality
Wally Melnitchouk
JLab

When hadronic cross sections are averaged over appropriate energy intervals, they often exhibit the scaling behavior expected from perturbative QCD calculations in terms of quarks and gluons. I will review a striking example of this quark-hadron duality, in inclusive electron-nucleon scattering, which exposes the close relationship between resonances and scaling structure functions. Using the operator product expansion, I will discuss how duality violations, in the form of higher-twist corrections, can be used to explore the nature of long-distance correlations between partons in the nucleon.