VECTOR-MESONS IN ASYMMETRIC NUCLEAR-MATTER

The propagation of a vector meson (rho and omega) in dense asymmetric nuclear matter (with the number density of protons and neutrons differ ent) is studied. Of particular interest is the density dependence of t he vector meson masses, as also their variation with the asymmetry par ameter, mass splitting among the rho isospin multiplets and the change of the form of the rho meson self-energy or the polarization tenser ( Pi(mu nu)) when the p<->n symmetry is broken, Contributions of both th e Fermi sea and Dirac vacuum have been considered. It is shown that wh ile the density dependent dressing of the vector meson propagator lift s the dispersion characteristics into the region of instability, the D irac vacuum on the other hand contributes with opposite sign, thereby enhancing the possibility of stable collective modes even for higher v alues of vector meson momenta. The role of tenser coupling on the disp ersion characteristics is also presented.