General Issues in Small-x and Diffractive Physics

Abstract

A selected review of topics at the border of hard and soft physics is given. Particular emphasis is a placed on diffraction dissociation at Fermilab and HERA. Recently, significant differences between diffraction dissociation at HERA and at Fermilab have become apparent. This may suggest that one already is reaching nonlinear (unitarity) effects which are extending from the soft physics region into the semihard regime of QCD.

Comments: 18 pages, Latex, Zeitschrift Fur Physik C. Particles & Fields