Spin and hard processes

Abstract

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