Asymmetric nuclear matter from an extended Brueckner-Hartree-Fock approach

The properties of isospin-asymmetric nuclear matter have been investigated in the framework of the extended Brueckner-Hartree-Fock approximation at zero temperature. Self-consistent calculations using the Argonne ${V}_{14}$ interaction are reported for several values of the asymmetry parameter $\ensuremath{\beta}=(N\ensuremath{-}Z)/A,$ ranging from symmetric nuclear matter to pure neutron matter. The binding energy per nucleon fulfills the ${\ensuremath{\beta}}^{2}$ law in the whole asymmetry range. The symmetry energy is calculated for different densities and discussed in comparison with other predictions. At the saturation point it is in fairly good agreement with the empirical value. The present approximation, based on the Landau definition of quasiparticle energy, is investigated in terms of the Hugenholtz--Van Hove theorem, which is proved to be fulfilled with a good accuracy at various asymmetries. The isospin dependence of the single-particle properties is discussed, including mean field, effective mass, and mean free path of neutrons and protons. The isospin effects in nuclear physics and nuclear astrophysics are briefly discussed.