1,615 research outputs found
A simple model for the microscopic effective pairing interaction
The microscopic effective pairing interaction in the -channel is
investigated for two different values of the chemical potential starting
from the separable form of the Paris NN-potential. It is shown that, within a
high accuracy, this effective interaction can be approximated by the off-shell
free T-matrix taken at the negative energy .Comment: LaTeX, 8 pages, 6 ps-figure
Spin degrees of freedom and flattening of the spectra of single-particle excitations in strongly correlated Fermi systems
The impact of long-range spin-spin correlations on the structure of a flat
portion in single-particle spectra , which emerges beyond the point,
where the Landau state loses its stability, is studied. We supplement the
well-known Nozieres model of a Fermi system with limited scalar long-range
forces by a similar long-range spin-dependent term and calculate the spectra
versus its strength . It is found that Nozieres results hold as long as
. However, with changing its sign, the spontaneous magnetization is
shown to arise at any nonzero . The increase of the strength is
demonstrated to result in shrinkage of the domain in momentum space, occupied
by the flat portion of , and, eventually, in its vanishing.Comment: 7 pages, 15 figure
Spatial correlation properties of the anomalous density matrix in a slab of nuclear matter with realistic NN-forces
Spatial correlation characteristics of the anomalous density matrix
in a slab of nuclear matter with the Paris and Argonne v18 forces are
calculated. A detailed comparison with predictions of the effective Gogny force
is made. It is found that the two realistic forces lead to very close results
which are qualitatively similar to those for the Gogny force. At the same time,
the magnitude of for realistic forces is essentially smaller than the
one for the Gogny force. The correlation characteristics are practically
independent of the magnitude of and turn out to be quite close for the
three kinds of the force. In particular, all of them predict a small value of
the local correlation length at the surface of the slab and a big one, inside.
These results are in agreement with those obtained recently by Pillet at al.
for finite nuclei with the Gogny force.Comment: 19 pages, 13 figure
Surface behaviour of the pairing gap in semi-infinite nuclear matter
The -pairing gap in semi-infinite nuclear matter is evaluated
microscopically using the effective pairing interaction recently found
explicitly in the coordinate representation starting from the separable form of
the Paris NN-potential. Instead of direct iterative solution of the gap
equation, a new method proposed by V.A.Khodel, V.V.Khodel and J.W.Clark was
used which simplifies the procedure significantly. The gap obtained in
our calculations exibits a strong variation in the surface region with a
pronounced maximum near the surface.Comment: 9 pages, 2 ps figure
Existence of nuclei with unusual neutron excess
Abstract A realistic model is suggested based on the quasiparticle Lagrange version of the self-consistent Finite Fermi Systems theory supplemented with the microscopically calculated surface parameters of the Landau–Migdal interaction amplitude. The latter are expressed in terms of the off-shell T -matrix of free NN -scattering and show a strong dependence on the chemical potential of a nucleus under consideration in the drip line vicinity. This effect could result in shifting the neutron drip line position to very large values of the neutron excess
- …