Spin and hard processes

It is argued that spin is a fundamental aspect of gauge theories at short distances. As a consequence there are characteristic helicity asymmetries in hard inclusive and exclusive reactions of which a few are discussed.Comment: 8 pages, 5 figures (using LATEX with ws-procs9x6.cls), talk presented at the 2nd international symposium on the Gerasimov-Drell-Hearn sum rule and the spin structure of the nucleon, Genova, July 200

A modern view of wide-angle exclusive scattering

The basic theoretical ideas of the handbag mechanism for wide-angle exclusive scattering reactions are discussed and, with regard to the present experimental program carried out at JLab, its application to Compton scattering is reviewed in some detail. Results for other wide-angle reactions such as two-photon annihilations into pairs of hadrons or virtual Compton scattering are presented as well.Comment: 10 pages, 6 figures (using LATEX with ws-procs9x6.cls), talk presented at the Nstar2002 workshop on the physics of excited nucleons, Pittsburgh, October 200