Nucleon matrix elements of various four-quark operators are evaluated in quenched lattice QCD using Wilson fermions. Some of these operators give rise to twist-four contributions to nucleon structure functions. Furthermore, they bear valuable information about the diquark structure of the nucleon. Mixing with lower-dimensional operators is avoided by considering appropriate representations of the flavour group. We find that for a certain flavour combination of baryon structure functions, twist-four contributions are very small. This suggests that twist-four effects for the nucleon might be much smaller than m_p^2/Q^2.
Cite
@article{arxiv.hep-lat/0103038,
title = {A lattice evaluation of four-quark operators in the nucleon},
author = {M. Göckeler and R. Horsley and B. Klaus and D. Pleiter and P. E. L. Rakow and S. Schaefer and A. Schäfer and G. Schierholz},
journal= {arXiv preprint arXiv:hep-lat/0103038},
year = {2008}
}