Hard diffraction in hadron-hadron interactions and in photoproduction

Hard single diffractive processes are studied within the framework of the triple-Pomeron approximation. Using a Pomeron structure function motivated by Regge theory we obtain parton distribution functions which do not obey the momentum sum rule. Based on Regge factorization, cross sections for hard diffraction are calculated. Furthermore, the model is applied to hard diffractive particle production in photoproduction and in pp¯ interactions.