QCD Sum Rule Calculation of Twist-3 Contributions to Polarized Nucleon   Structure Functions
  Using the framework of QCD sum rules we predict the twist-3 contribution to the second moment of the polarized nucleon structure function $g_2(x)$. As the relevant local operator depends explicitely on the gluon field, we employ a recently studied interpolating nucleon current which contains three quark field and one gluon field operator. Despite the fact that our calculation is based on the analysis of a completely different correlation function, our estimates are consitent with those of Balitsky, Braun and Kolesnichenko who used a three-quark current. 
E. Stein, P. Gornicki, L. Mankiewicz, A. Schaefer, W. Greiner