Deep Inelastic Structure Functions in a Covariant Spectator Model
  Deep-inelastic structure functions are studied within a covariant scalar diquark spectator model of the nucleon. Treating the target as a two-body bound state of a quark and a scalar diquark, the Bethe-Salpeter equation (BSE) for the bound state vertex function is solved in the ladder approximation. The valence quark distribution is discussed in terms of the solutions of the BSE. 
K. Kusaka, G. Piller, A.W. Thomas and A.G. Williams