LPS provides access to new fundamental observables: the diffraction cone and azimuthal asymmetries. Diffraction cone has a unique rise of $B_T$ from the exclusive limit to excitation of continuum $M^2 approx Q^2$ which is in striking contrast to experience with real photoproduction and hadronic diffraction. Azimuthal asymmetry is large and pQCD calculable at large $beta$ and can be measured with LPS. It allows testing of the pQCD prediction of $L/T >> 1$.
We calculate the diffraction slope $B_{D}$ for diffractive DIS. We find a counterintuitive rise of $B_{D}$ from exclusive diffractive excitation of vector mesons to excitation of continuum states with $M^{2} sim Q^{2}$. For the small-mass continuum we predict a rapid variation of $B_{D}$ with $M^{2}$ on the scale $m_{V}^{2}$ and a sharp drop of $B_{D}$ for a small-mass continuum above the vector meson excitation.
We propose a new method of the determination of $R^{D}=sigma_{L}^{D}/sigma_{T}^{D}$ from the dependence of the diffractive cross section on the azimuthal angle between the electron scattering and proton scattering planes. The method is based on our finding of the model independence of the ratio of the $LT$ interference and transverse diffractive structure functions. The predicted azimuthal asymmetry is substantial and can be measured at HERA. We show that the accuracy of our reconstruction of $R^{D}$ is adequate for a reliable test of an important pQCD prediction of $R^{D}gsim 1$ for large $beta$.
A new method of extracting diffractive parton distributions is presented which avoids the use of Regge theory ansatz and is in much closer relation with the factorisation theorem for diffractive hard processes.
We report on investigations concerning the production of large transverse momentum jets in DIS diffractive dissociation. These processes constitute a new class of events that allow for a clean test of perturbative QCD and of the hard (perturbative) pomeron picture. The measurement of the corresponding cross sections might possibly serve to determine the gluon density of the proton.
We discuss recent theoretical results on diffractive deeply inelastic scattering, focusing on the partonic picture of diffraction in configuration space and the predictions for the beta behavior and the scaling violation.