MEDIUM EFFECTS IN THE PRODUCTION AND DECAY OF OMEGA-RESONANCES AND RHO-RESONANCES IN PION-NUCLEUS INTERACTIONS

The omega- and rho-resonance production and their dileptonic decay in pi(-)A reactions at GSI energies are calculated within the intranuclea r cascade (INC) approach. The invariant mass distribution of the dilep ton pair for each resonance is found to have two components which corr espond to the decay of the resonances outside and inside the target nu cleus. The latter components are strongly distorted by the nuclear med ium due to resonance-nucleon scattering and a possible mass shift at f inite baryon density. These medium modifications are compared to backg round sources in the dilepton spectrum from pi N bremsstrahlung and th e Dalitz decays of Delta's, omega and eta mesons produced in the react ion. (C) 1997 Elsevier Science B.V.