PROTON FRAGMENTATION IN HIGH ENERGY COLLISIONS Patrik Ede'n, Master Thesis Thesis advisor: Gosta Gustafson Simulations of nucleon collisions based on the Lund fragmentation scheme are not fully satisfactory at present. Though succesful in reproducing meson spectra, they fail with respect to baryon spectra in the fragmentation regions. It is therefore reasonable to look for a more careful treatment of the diquark end in a fragmenting baryon string. In this paper we introduce a new version of the so called J-quark Model - a model of the inner structure of such a diquark. We show that simulations of pp-collisions using an algorithm taking this model into account improve fits to experimental data. Further improvements within the framework of this model are discussed. LU TP 94-20 November 1994