Nucleon properties in nuclear medium

The modifications of the nucleon structure due to the presence of an external baryon medium are investigated. To that end the Nambu-Jona-Lasinio model is used to evaluate the pion decay constant and the pion and sigma masses at finite density. Those meson properties serve to fix the parameters of the linear chiral sigma model, which is then solved in a variational projected mean field approach in order to obtain nucleon properties. The proton radius shows an increase of 19% and the nucleon mass a decrease of 17% if the medium reaches nuclear matter density. The magnetic moments and axial vector coupling constant are less modified whereas the pion nucleon coupling constant stays practically constant at increasing medium density. All form factors show remarkable reduction at finite transfer momenta. (author). 20 refs, 8 figs, 1 tab