Pions in the nuclear medium and Drell-Yan scattering

We investigate the modification of the pion-cloud in the nuclear medium and its effect on the nuclear Drell-Yan process. The pion's in-medium self-energy is calculated in a self-consistent delta-hole model, with particle-hole contribution also included. Both the imaginary and real part of the pion's and delta's self-energy are taken into account and related through a dispersion relation assuring causality. The resulting in-medium pion light-cone momentum distribution shows only a slight enhancement compared to the one of the free nucleon. As a consequence the ratio of the cross-section for Drell-Yan scattering on nuclear matter and nucleonic target is close to unity in agreement with experiment.