[en] Quark-hadron duality addresses some of the most fundamental issues in strong interaction physics, in particular the nature of the transition from the perturbative to non-perturbative regions of QCD. 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 Jefferson Lab at 12 GeV, or an electron-hadron collider such as EPIC

[en] Asymmetries in the quark momentum distributions in the proton reveal fundamental aspects of strong interaction physics. Differences between (anti u) and (anti d) quarks in the proton sea provide insight into the dynamics of the pion cloud around the nucleon and the nature of chiral symmetry breaking. Polarized flavor asymmetries allow the effects of pion clouds to be disentangled from those of antisymmetrization. Asymmetries between s and (anti s) quark distributions in the nucleon are also predicted from the chiral properties of QCD

[en] Asymmetries in the quark momentum distributions in the proton reveal fundamental aspects of strong interaction physics. Differences between (anti u) and (anti d) quarks in the proton sea provide insight into the dynamics of the pion cloud around the nucleon and the nature of chiral symmetry breaking. Polarized flavor asymmetries allow the effects of pion clouds to be disentangled from those of antisymmetrization. Asymmetries between s and (anti s) quark distributions in the nucleon are also predicted from the chiral properties of QCD

[en] The authors examine the consequences of local duality for elastic scattering, and derive model-independent relations between structure functions at xapproximately1 and elastic electromagnetic form factors

[en] The author reviews some recent developments in the study of quark flavor distribution in the nucleon, including (1) valence quark distributions and quark-hadron duality prediction for the x r_arrow 1 Fⁿ₂/F^p₂ ration (2) sea quark asymmetries and electromagnetic form factors (3) strange quarks in the nucleon

[en] Recent data on the proton F₂ structure function in the resonance region suggest that local quark-hadron duality works remarkably well for each of the low-lying resonances, including the elastic, to rather low values of Q² . We derive model-independent relations between structure functions at x∼1 and elastic electromagnetic form factors, and predict the x→1 behavior of nucleon polarization asymmetries and the neutron to proton structure function ratios from available data on nucleon electric and magnetic form factors

[en] The internal structure of the nucleon is discussed within the context of QCD. Recent progress in understanding the distribution of flavor and spin in the nucleon is reviewed, and prospects for extending the author's knowledge of nucleon structure in electron scattering experiments at modern facilities such as Jefferson Lab are outlined

[en] We discuss the origin of Bloom-Gilman duality and the relationship between resonances and scaling in deep-inelastic scattering. We present a simple quantum mechanical model which reproduces the essential features of Bloom-Gilman duality at low Q², and describe applications of local duality relating structure functions at xapproximately1 and elastic electromagnetic form factors

[en] Recent analyses of electromagnetic structure functions in the resonance region suggest that duality-violating higher twists are small above Q² ∼ 1 GeV². We review duality at the resonance--scaling transition, both phenomenologically and in the context of a simple quark model. While most studies have focused on electromagnetic probes, we also discuss expectations for the workings of duality in neutrino scattering. Finally, we describe the transition of the structure functions to the photoproduction limit at Q²=0

[en] Recent data on the proton F₂ structure function in the resonance region suggest that local quark-hadron duality works remarkably well for each of the low-lying resonances, including the elastic, to rather low values of Q². The authors discuss model-independent relations between structure functions x∼1 and elastic electromagnetic form factors. The xr_arrow1 behavior of the nucleon polarization asymmetries and the neutron to proton structure function ratios is studied as a function of Q-squared using available data on the electric and magnetic form factors