t-dependence in "diffractive" deep inelastic scattering: a case for "colour-filtered" perturbation theory

We show how an incorrect prediction of the t-dependence of diffractive deep inelastic scattering in the Anisotropic Chrome-Dynamics (ACD) framework wa s due to the erroneous evaluation of colour-traces through the perturbation theory prescription. By employing the "colour filtering" required by colou r confinement, good agreement with experiment is obtained. As a result we e xtend our discussion to the diagrams of PQCD and we argue that submitting t hem to "colour filtering" removes their inconsistency with quark confinemen t and with the basic ideas of ACD. (C) 2000 Elsevier Science B.V. All right s reserved.