An analysis of the next-to-leading order corrections to the gT(=g1+g2) scaling function

We present a general method for obtaining the quantum chromodynamical radiative corrections to the higher-twist (power-suppressed) contributions to inclusive deep-inelastic scattering in terms of light-cone correlation functions of the fundamental fields of quantum chromodynamics. Using this procedure, we calculate the previously unknown O(alpha (S)) corrections to the twist-three part of the spin scaling function g(T) (x(B), Q(2))(= g(1) (x(B), Q(2)) + g(2)(x(B), Q(2))) and the corresponding forward Compton amplitude ST (v, Q2). Expanding our result about the unphysical point x(B) = infinity, we arrive at an operator product expansion of the nonlocal product of two electromagnetic current operators involving twist-two and -three operators valid to O(alpha (S)) for forward matrix elements. We find that the Wandzura-Wilczek relation between g(1) (x(B), Q(2)) and the twist-two part of g(T) (X-B, Q(2)) is respected in both the singlet and non-singlet sectors at this order, and argue its validity to all orders. The large-N-C limit does not appreciably simplify the twist-three Wilson coefficients. (C) 2001 Elsevier Science B.V. All rights reserved.