Nuclear Drell-Yan effect in a covariant model

We investigate effects of nuclear medium on antiquark distribution in nuclei applying the results of a recently developed relativistically-covariant self-consistent model for the pion and the isobar. We take into account Fermi motion including Pauli blocking and binding effects on the nucleons and medium effects on the isobar and pion leading to modest enhancement of the pion light-cone-momentum distribution in large nuclei. As a consequence the Drell-Yan cross-section ratio with respect to the deuteron exceeds one only for small values of the light-cone momentum.