Photon diffractive dissociation in deep-inelastic scattering

This paper is mainly devoted to the presentation and discussion of formulas for the cross section of photon diffractive dissociation. The calculations which we present in a very detailed way are based on perturbative QCD. We improve formulas which describe this process in the triple Regge limit where the square of the missing mass ${\mathit{M}}_{\mathit{X}}$ (the invariant mass of the bunch of secondary hadrons) is much larger than ‖${\mathit{Q}}^2$‖ and extend the range of validity to the region where ${\mathit{M}}_{\mathit{X}}^2$ is of the same order as ‖${\mathit{Q}}^2$‖. We introduce a diffractive dissociation structure function and show that it obeys the Gribov-Lipatov-Altarelli-Parisi evolution equation, but, with an additional inhomogeneous term. The relation to the Pomeron structure function is discussed.