ρ-meson properties at finite nuclear density

We calculate the momentum dependence of the rho-meson self-energy based on the dispersion relation for the rho N scattering amplitude f(omega) at low nuclear density. The imaginary part of f(w) is determined from the optical theorem, while the total rho N cross section is obtained within the vector dominance model at high energy and within the resonance model at low energy. Our numerical results indicate a sizable broadening of the rho-meson width in the medium especially for low relative momenta p while the real part of the rho self-energy is found to change its sign and to become repulsive already at momenta above 100 MeV/c. Extrapolating to nuclear saturation density rho(0) we find a dropping of the rho mass for p approximate to 0 roughly in line with the QCD sum rule analysis of Hatsuda while at high energy an increase of the rho mass close to the prediction by Eletsky and Ioffe is obtained. However, when including a broadening of the baryonic resonances in the medium, the rho-meson mass shift at p approximate to 0 becomes slightly repulsive, whereas the width increases substantially.