87 research outputs found
Upper edge of the neutron star crust : the drip point and around
A semi-microscopic self-consistent quantum approach developed recently to
describe the inner crust structure of neutron stars within the Wigner-Seitz
method with the explicit inclusion of neutron and proton pairing correlations
is used for finding the neutron drip point which separates the outer and inner
crusts. The equilibrium configurations of the crust are examined in vicinity of
the drip point and in the upper part of the inner crust, for the density region
corresponding to average Fermi momenta fm.Comment: 22 pages, 6 figure
Local energy-density functional approach to many-body nuclear systems with s-wave pairing
The ground-state properties of superfluid nuclear systems with ^1S_0 pairing
are studied within a local energy-density functional (LEDF) approach. A new
form of the LEDF is proposed with a volume part which fits the Friedman-
Pandharipande and Wiringa-Fiks-Fabrocini equation of state at low and moderate
densities and allows an extrapolation to higher densities preserving causality.
For inhomogeneous systems, a surface term with two free parameters is added. In
addition to the Coulomb direct and exchange interaction energy, an effective
density-dependent Coulomb-nuclear correlation term is included with one more
free parameter, giving a contribution of the same order of magnitude as the
Nolen-Schiffer anomaly in Coulomb displacement energy. The root-mean-square
deviations from experimental masses and radii with the proposed LEDF come out
about a factor of two smaller than those obtained with the conventional
functionals based on the Skyrme or finite-range Gogny force, or on the
relativistic mean-field theory. The generalized variational principle is
formulated leading to the self-consistent Gor'kov equations which are solved
exactly, with physical boundary conditions both for the bound and scattering
states. With a zero-range density-dependent cutoff pairing interaction
incorporating a density-gradient term, the evolution of differential
observables such as odd-even mass differences and staggering in charge radii,
is reproduced reasonably well, including kinks at magic neutron numbers. An
extrapolation to infinite nuclear matter is discussed. We study also the dilute
limit in both the weak and strong coupling regime.Comment: 19 pages, 8 figures. LaTeX, with modified cls file supplied. To be
published in vol. 3 of the series "Advances in Quantum Many-Body Theory",
World Scientific (Proceedings of the MBX Conference, Seattle, September
10-15, 1999
Self-consistent calculations of quadrupole moments of the first 2+ states in Sn and Pb isotopes
A method of calculating static moments of excited states and transitions
between excited states is formulated for non-magic nuclei within the Green
function formalism. For these characteristics, it leads to a noticeable
difference from the standard QRPA approach. Quadrupole moments of the first 2+
states in Sn and Pb isotopes are calculated using the self-consistent TFFS
based on the Energy Density Functional by Fayans et al. with the set of
parameters DF3-a fixed previously. A reasonable agreement with available
experimental data is obtained.Comment: 5 pages, 6 figure
Microscopic evaluation of the pairing gap
We discuss the relevant progress that has been made in the last few years on
the microscopic theory of the pairing correlation in nuclei and the open
problems that still must be solved in order to reach a satisfactory description
and understanding of the nuclear pairing. The similarities and differences with
the nuclear matter case are emphasized and described by few illustrative
examples. The comparison of calculations of different groups on the same set of
nuclei show, besides agreements, also discrepancies that remain to be
clarified. The role of the many-body correlations, like screening, that go
beyond the BCS scheme, is still uncertain and requires further investigation.Comment: 21 pages,7 figures; minor modification, accepted for publication in
J. Phys.
Phonon effects on the double mass differences in magic nuclei
Odd-even double mass differences (DMD) of magic nuclei are found within the
approach starting from the free interaction with account for
particle-phonon coupling (PC) effects. We consider three PC effects: the phonon
induced effective interaction, the renormalization of the "ends" due to the
-factor corresponding to the pole PC contribution to the nucleon mass
operator and the change of the single-particle energies. The perturbation
theory in , where is the vertex of the -phonon creation, is
used for PC calculations.
PC corrections to single-particle energies are found self-consistently with
an approximate account for the tadpole diagram. Results for magic Ca,
Ni, Sn and Pb nuclei are presented. For lighter
part of this set of nuclei, from Ca till Ni, the cases divide
approximately in half between those where the PC corrections to DMD values make
agreement with the data better and the ones with the opposite result. In the
major part of the cases of worsening of description of DMD, a poor
applicability of the perturbation theory for the induced interaction is the
most probable reason of the phenomenon. For intermediate nuclei, Ni and
Sn, there is no sufficiently accurate data on masses of nuclei
necessary for finding DMD values. Finally, for heavier nuclei, Sn and
Pb, PC corrections always make agreement with the experiment better.Comment: LaTex, 12 pages, 6 figures, submitted to Phys. Rev. C. arXiv admin
note: text overlap with arXiv:1206.218
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