Pole term and gauge invariance in deep inelastic scattering

In this paper the authors reconcile two contradictory statements about deep inelastic scattering (DIS) in manifestly covariant theories: (1) the scattering must be gauge invariant, even in the deep inelastic limit, and (2) the pole term (which is not gauge invariant in a covariant theory) dominates the scattering amplitude in the deep inelastic limit. An ''intermediate'' answer is found to be true. They show that, at all energies, the gauge dependent part of the pole term cancels the gauge dependent part of the rescattering term, so that both the pole and rescattering terms can be separately redefined in a gauge invariant fashion. The resulting, redefined pole term is then shown to dominate the scattering in the deep inelastic limit. Details are worked out for a simple example in 1+1 dimensions