Speaker
Description
We resum the ladder diagrams for the calculation of the energy per particle E/A of a spin 1/2 fermion many-body system in terms of any given vacuum two-body scattering amplitudes. The partial-wave decomposition of the in-medium two-body scattering amplitudes is worked out, and the expression for calculating E/A in a partial-wave amplitude expansion is also given. The case of contact interactions is completely solved for any number of partial waves and it is shown to provide renormalized results, expressed directly in terms of scattering data parameters, within a generic cutoff regularization schemes. We first discuss the case of including S- and P-wave interactions characterized by the first three-terms in the effective-range expansion, paying special attention to the parametric region around the unitary limit. This scheme is applied to study the resulting equation of state for neutron and symmetric nuclear matter, specially suited for low density.