Gluon contribution to the structure function g(2)(x, Q(2))

We calculate the one-loop twist-3 gluon contribution to the flavor-singlet structure function g(2)(x, Q(2)) in polarized deep-inelastic scattering and find that it is dominated by the contribution of the three-gluon operator with the lowest anomalous dimension (for each moment N). The similar proper ty was observed earlier for the nonsinglet distributions, although the reas on is in our case different. The result is encouraging and suggests a simpl e evolution pattern of g(2)(x, Q(2)) in analogy with the conventional descr iption of twist-2 parton distributions. (C) 2001 Elsevier Science B.V. All rights reserved.