Hard diffraction from quasi-elastic dipole scattering

The contribution to diffraction dissociation of virtual photons due to quasi-elastic scattering of the q-q component is calculated in the framework of the QCD dipole picture. Both longitudinal and transverse components of the cross-section are given. It is shown that, at fixed mass of the diffractively produced system, quantum mechanical interference plays an important rôle. Phenomenological consequences are discussed.