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Conclusions

The soft pomeron does not describe all diffractive data measured at HERA. As the photon virtuality or the vector meson mass increase a new dependence on W2 emerges. As we investigate the pomeron more closely, a new type of dynamical pomeron may begin to play a rôle; a dynamical pomeron whose structure is being measured in DIS. These data are consistent with a partonic description of the exchanged object which may be described by pQCD.

The cross-sections for hard diffractive processes at HERA can be compared to those observed at the Tevatron. All data are consistent with a significant gluon contribution of the partons within the pomeron i.e. QCD factorisation appears to be observed. However, a universal pomeron flux does not describe the observed rates i.e. Regge factorisation does not apply. This is qualitatively expected from QCD corrections to the rates, but the effects are large and non-perturbative.

The experimental work focuses on extending the lever arms and increasing the precision in t, M2, W2 and Q2 in order to explore this new structure. Before more precise tests can be made, further theoretical and experimental input is required to reduce the uncertainties due to non-diffractive backgrounds and proton dissociation as well as the treatment of FL and radiative corrections.


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Next: Acknowledgements Up: Diffraction: QCD Effects in Previous: Diffraction at the Tevatron
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