PHOTON DIFFRACTIVE DISSOCIATION IN DEEP-INELASTIC SCATTERING

This paper is mainly devoted to the presentation and discussion of for mulas for the cross section of photon diffractive dissociation. The ca lculations which we present in a very detailed way are based on pertur bative QCD. We improve formulas which describe this process in the tri ple Regge limit where the square of the missing mass M(X) (the invaria nt mass of the bunch of secondary hadrons) is much larger than \Q2\ an d extend the range of validity to the region where M(X)2 is of the sam e order as \Q2\. We introduce a diffractive dissociation structure fun ction and show that it obeys the Gribov-Lipatov-Altarelli-Parisi evolu tion equation, but, with an additional inhomogeneous term. The relatio n to the Pomeron structure function is discussed.