Parton interpretation of the nucleon spin-dependent structure functions

Abstract

We discuss the interpretation of the nucleon’s polarized structure function ${\mathit{g}}_2$(x). If the target state is represented by its Fock decomposition on the light cone, the operator-product expansion allows us to demonstrate that moments of ${\mathit{g}}_2$(x) are related to overlap integrals between wave functions of opposite longitudinal polarizations. In the light-cone formalism such wave functions are related by the kinematical operator scrY, or light-cone parity. As a consequence, it can be shown that moments of ${\mathit{g}}_2$ give information about the same parton wave function, or probability amplitude to find a certain parton configuration in the target which defines ${\mathit{g}}_1$(x) or ${\mathit{F}}_2$(x). Specific formulas are given, and possible applications to the phenomenology of the nucleon structure in QCD are discussed.