VECTOR-MESONS IN NUCLEAR MEDIUM - AN EFFECTIVE LAGRANGIAN APPROACH

Several authors have shown that the mass of the omega-meson decreases in nuclear medium using the Walecka model. We generalize the approach to the rho-meson and show that both the pole position and the screening mass decrease in nuclear matter due to the polarization of the nucleon Dirac sea. The physical origin of the decrease is a reduction of the wave function renormalization constant induced by the rhoNN tensor coupling. A comparison of our result with that in the QCD sum rules is also made.