Screening effects in superfluid nuclear and neutron matter within Brueckner theory

Effects of medium polarization are studied for ${}^{1}{S}_{0}$ pairing in neutron and nuclear matter. The screening potential is calculated in the RPA limit, suitably renormalized to cure the low density mechanical instability of nuclear matter. The self-energy corrections are consistently included resulting in a strong depletion of the Fermi surface. All medium effects are calculated based on the Brueckner theory. The ${}^{1}{S}_{0}$ gap is determined from the generalized gap equation. The self-energy corrections always lead to a quenching of the gap, which is enhanced by the screening effect of the pairing potential in neutron matter, whereas it is almost completely compensated by the antiscreening effect in nuclear matter.