The evolution of the nonsinglet twist-3 parton distribution function

Abstract

The twist three contributions to the $Q^2$-evolution of the spin-dependent structure function $g_2(x_{Bj},Q^2)$ are considered in the non-local operator product approach. Defining appropriate twist three distribution function we derive their evolution equation for the nonsinglet case in leading order approximation. In the limit $x_{Bj}\to 1$ as well as in the large $N_c$ limit we confirm the result that the evolution of the nonsinglet part of $g_2$ is governed by a Gribov-Lipatov-Altarelli-Parisi equation.

8 pages Latex An earlier version of this paper has been presented at the `3rd Meeting on the Prospects of Nucleon-Nucleon Spin Physics at HERA', JINR Dubna, 28-29 June 1996