Renormalization of four-fermion operators for higher twist calculations
  The evaluation of the higher twist contributions to Deep Inelastic Scattering amplitudes involves a non trivial choice of operator bases for the higher orders of the OPE expansion of the two hadronic currents. In this talk we discuss the perturbative renormalization of the four-fermion operators that appear in the above bases. 
S. Capitani, M. G\"ockeler, R. Horsley, H. Perlt, P.E.L. Rakow, G.   Schierholz, A. Schiller