Collective modes in a slab of interacting nuclear matter

We study the properties of a slab of nuclear matter. The behaviour with the slab thickness of the particle density, kinetic energy density and surface tension are given in the non-interacting case, together with the slab free response to an external field. Next we introduce a zero-range isovector interaction among the nucleons and analyze the slab collective excitations. For moderate momenta hard and soft modes are found, which exhaust most of the excitation strength. Their position and splitting in energy favourably compares with the splitted giant dipole resonance experimentally seen in deformed nuclei.