TWIST-4 CONTRIBUTIONS TO THE HADRON STRUCTURE FUNCTIONS

We present a new method for calculating the twist-4 contributions to the hadron structure functions. This new method leads to a clear space-time picture of twist-4 short-distance contributions and makes manifest the preservation of the underlying gauge invariance. The use of our new method results in a significant reduction in labor relative to past calculations of higher-twist contributions. In our new approach, the twist-4 short-distance contributions to the hadronic structure functions arise from the complete imaginary part of a photon-parton forward-scattering amplitude, and, hence, they can be given a simple parton-model interpretation. Possible tests of such twist-4 contributions are also discussed. © 1990 The American Physical Society.