Effective vector meson masses in a cutoff field theory

Based on quantum hadrodynamics with a finite cutoff, the effective masses o f vector mesons (omega, rho) in nuclear medium are calculated. We use a low -energy effective Lagrangian which is obtained by integrating high-energy q uantum fluctuations. Although we use an artificial cutoff, the cutoff-depen dence can be removed order by order. It is also found that the effective rh o-meson mass m(rho)* decreases as the density increases. The rate of the de crease becomes smaller at high density. As a result, at the normal density, m(rho)*/m(rho) is 0.85 similar to 0.92.