Self-consistent many-body approach and properties of neutron star matter

TOBIAS FRICK; KHALAF GAD; JAN KUCKEI; FERNANDO MONTANI; HERBERT MÜTHER

Münster (Germany)

Congreso; Deutsche Physikalische Gesellschaft (DPG); 2002

Sociedad de Fisica Alemana

Within a Green's functions approach, the neutron and the proton properties are studied in asymmetric nuclear matter, starting from realistic NN potentials. Going beyond a quasi-particle approximation, we account for the depletion of the hole states in the many-body system by introducing multiple poles in the two-particle propagator that appears in the ladder-equation for the effective interaction, each of them carrying a strength that is deduced from the nuclear single-particle spectral functions. The nuclear self-energies are calculated within different approximations, treating the backward-propagation of intermediate two-hole-one-particle configurations perturbatively, but also in a non-perturbative Galitsii-Feynman approach. Due to a non-vanishing spectral distribution of the single-particle strength for momenta very close to the Fermi surface, a gap is introduced in the single-particle spectrum. In a natural way, this leads to a supression of the well-known pairing instability. The results of this Green's function approach for the equation of state are compared to corresponding predicitions of the conventional Brueckner-Hartree-Fock approach. Furthermore we present the predicitions for the spectral function and momentum distribution. The sensitivity of theses on the NN interaction is discussed.