2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/202426Nucleon 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^2.17 pages, 3 figuresHigh Energy Physics - LatticeHigh Energy Physics - Phenomenologytext