The Spin Structure of the Nucleon: Theoretical Overview

Abstract

I review what is known about the quark and gluon spin distributions in the nucleon. I discuss in some detail (a) the existence of sum rules for angular momentum; (b) the interpretation and possible measurement of the nucleon's transversity distributions; and (c) the uses of spin-dependent fragmentation functions.

Comments: 20 pages, 9 figures, using Revtex and BoxedEPS macros; email to <jaffe@mit.edu>; presented at the Second Workshop on Physics with a Polarized-Electron Light-Ion Collider (EPIC), September 14--16, 2000 at MIT, Cambridge, MA, USA