Probing Quark-Gluon Interactions with Transverse Polarized Scattering
  We have extracted QCD matrix elements from our data on double polarized inelastic scattering of electrons on nuclei. We find the higher twist matrix element \tilde{d_2}, which arises strictly from quark- gluon interactions, to be unambiguously non zero. The data also reveal an isospin dependence of higher twist effects if we assume that the Burkhardt-Cottingham Sum rule is valid. The fundamental Bjorken sum rule obtained from the a0 matrix element is satisfied at our low momentum transfer. 
K. Slifer, O.A. Rondon, A. Aghalaryan, A. Ahmidouch, R. Asaturyan, F.   Bloch, W. Boeglin, P. Bosted, C. Carasco, R. Carlini...