On the pomeron structure function in QCD

The concept of a pomeron structure function, introduced in connection with “hard diffractive scattering”, is here discussed in terms of gluon ladders and fan diagrams in perturbative QCD. We find that the gluon distribution of the pomeron is in many cases dominated by non-perturbative effects, which support earlier work based on Regge theory. There are cases, however, where perturbative QCD effects dominate and the Regge-based treatment is incorrect. In all cases, perturbative QCD can be used to gain understanding of the pomeron and give predictions to be tested at pp colliders and at HERA