Abstract:

“The odd-even staggering of nuclear masses was recognized in the early days of nuclear physics. Recently, a similar effect was discovered in other finite fermion systems, such as ultrasmall metallic grains and metal clusters. It is believed that the staggering in nuclei and grains is primarily due to pairing correlations (superconductivity), while in clusters it is caused by the Jahn-Teller effect. We find that, for light and medium-mass nuclei, the staggering has two components. The first one originates from pairing while the second, comparable in magnitude, has its roots in the deformed mean field.”

arXiv:9804060v1 [nucl-th] [PDF]

Abstract:

“Models based on extended Thomas–Fermi and Strutinsky integral (ETFSI),
Hartree–Fock+BCS (HFBCS) and Hartree–Fock–Bogolyubov (HFB) mean-
field approximations with a phenomenological Skyrme functional, that are used
in the calculation of atomic masses, are reviewed. The main physics content
of these models is briefly described, both for finite nuclei and infinite nuclear
matter. For finite nuclei, the discussion focuses on the treatment of deformation,
odd-A and odd–odd nuclei, pairing and the correction for the Wigner anomaly.
In infinite nuclear matter, the effective nucleon mass in nuclear matter and
the symmetry energy and its density dependence are discussed. To further
test the validity of the Skyrme functional parameter sets, deduced from fits
to mass-data, the equation of state (EOS) for a symmetric beta-equilibrium
nuclear matter is constructed. The EOS, supplemented at baryon number
densities(0.08>nb >0.00025) fm−3 by Baym–Bethe–Pethick (BBP) EOS
and below that by Baym–Pethick–Sutherland (BPS) EOS, isused to predict
maximum mass and radius of cold (T=0) non-rotational neutron stars as
well as the binding energy and radius of a 1.4M star.  The present analysis
has shown that there is no significant improvement either in the rms error of
fit of the Hartree–Fock mass models to existing mass-databases, or to new
mass-data, with increasing sophistication of the models and the related number
of fitting parameters. Further, the Skyrme functionals obtained from fits to
nuclear masses cannot be successfully used in neutron-star models. This casts
doubt on the suitability of these functionals for the description of neutron–
heavy nuclei close to and beyond the neutron drip line. It is concluded that it
is unlikely that the present HF mass models will ever yield atomic masses with
the higher precision required by the r-process and related applications and a
different approach to the calculation of masses should be sought”.

J Rikovska Stone 2005 J. Phys. G: Nucl. Part. Phys. 31 R211-R230

Abstract:

“We show that pseudospin symmetry in nuclei could arise from nucleons moving in a relativistic
mean field which has an attractive scalar and repulsive vector potential nearly equal in magnitude.”

arXiv:9611044v1 [nucl-th] [PDF]

Abstract:

“We present a shell model calculation for the beta decay of 14-C to the 14-N ground-state, treating the relevant nuclear states as two 0p-holes in an 16-O core. Employing the universal low-momentum nucleon-nucleon potential V(low-k) only, one finds that the Gamow-Teller matrix element is too large to describe the known (very long) lifetime of 14-C. As a novel approach to the problem, we invoke the chiral three-nucleon force (3NF) at leading order and derive from it a density-dependent in-medium NN interaction. Including this effective in-medium NN interaction, the Gamow-Teller matrix element vanishes for a nuclear density close to that of saturated nuclear matter. The genuine short-range part of the three-nucleon interaction plays a particularly important role in this context, since the medium modifications to the pion propagator and pion-nucleon vertex (due to the long-range 3NF) tend to cancel out in the relevant observable. We discuss also uncertainties related to the off-shell extrapolation of the in-medium NN interaction. Using the off-shell behavior of V(low-k) as a guide, we find that these uncertainties are rather small.”

arXiv:0901.4750v1 [nucl-th] [PDF]

Abstract:

“We present shell model calculations for the beta-decay of the 14C ground state to the 14N ground state, treating the states of the A=14 multiplet as two 0p holes in an 16O core. We employ low-momentum nucleon-nucleon (NN) interactions derived from the realistic Bonn-B potential and find that the Gamow-Teller matrix element is too large to describe the known lifetime. By using a modified version of this potential that incorporates the effects of Brown-Rho scaling medium modifications, we find that the GT matrix element vanishes for a nuclear density around 85% that of nuclear matter. We find that the splitting between the (J,T)=(1+,0) and (J,T)=(0+,1) states in 14N is improved using the medium-modified Bonn-B potential and that the transition strengths from excited states of 14C to the 14N ground state are compatible with recent experiments.”

arXiv:0710.0310v2 [nucl-th] [PDF]