Symmetry Energy Of Nuclei Research Articles

Symmetry energy in nuclei and neutron stars

Abstract The symmetry energy plays an important role in nuclear astrophysics, ranging from the structure of nuclei to gravitational collapse to neutron stars. The BBAL paper by Bethe, Brown, et al., was among the first to recognize its importance. The role of the symmetry energy has evolved since that time when it represented one of the major uncertainties in modeling the equation of state of dense nuclear matter. At present, the parameters of the nuclear symmetry energy are tightly constrained by a concordance achieved from nuclear experiment, astrophysical observations, and ab initio theoretical calculations of neutron matter.

Symmetry energy and neutron-proton radii studied with a Wigner-Heisenberg monopole-monopole interaction

The symmetry energy in nuclei is studied using a monopole-monopole two boby interaction which has an isospin dependent term. A Hartree theory is developed for this interaction which has an oscillator shell model basis with corresponding shell structure. The role of shell structure on the symmetry energy is then studied. We also find that the strength of the Heisenberg interaction is very important for understanding the difference between proton and neutron radii and features associated with halo nuclei. PACS numbers: 21.10.Sf, 21.65Cd, 21.65Ef

Surface symmetry energy of nuclear energy density functionals

We study the bulk deformation properties of the Skyrme nuclear energy density functionals (EDFs). Following simple arguments based on the leptodermous expansion and liquid drop model, we apply the nuclear density functional theory to assess the role of the surface symmetry energy in nuclei. To this end, we validate the commonly used functional parametrizations against the data on excitation energies of superdeformed band heads in Hg and Pb isotopes and fission isomers in actinide nuclei. After subtracting shell effects, the results of our self-consistent calculations are consistent with macroscopic arguments and indicate that experimental data on strongly deformed configurations in neutron-rich nuclei are essential for optimizing future nuclear EDFs. The resulting survey provides a useful benchmark for further theoretical improvements. Unlike in nuclei close to the stability valley, whose macroscopic deformability hangs on the balance of surface and Coulomb terms, the deformability of neutron-rich nuclei strongly depends on the surface symmetry energy; hence, its proper determination is crucial for the stability of deformed phases of the neutron-rich matter and description of fission rates for r-process nucleosynthesis.

Strange and heavy flavoured hypernuclei in chiral soliton models

The extension of the chiral soliton approach to hypernuclei --strange or heavy flavoured-- becomes more reliable due to the success in describing other properties of nuclei, e.g. the symmetry energy of nuclei with atomic numbers up to ∼ 30 . The binding energies of the ground states of light hypernuclei with S = - 1 have been described in qualitative agreement with data. The existence of charmed or beautiful hypernuclei and Theta-hypernuclei (strange, charmed or beautiful) with large binding energy is expected within same approach.

The symmetry energy in nuclei and in nuclear matter

We discuss to what extent information on ground-state properties of finite nuclei (energies and radii) can be used to obtain constraints on the symmetry energy in nuclear matter and its dependence on the density. The starting point is a generalized Weizsacker formula for ground-state energies. In particular, effects from the Wigner energy and shell structure on the symmetry energy are investigated. Strong correlations in the parameter space prevent a clear isolation of the surface contribution. Use of neutron skin information improves the situation. The result of the analysis appears consistent with a rather soft density dependence of the symmetry energy in nuclear matter.

THE SYMMETRY ENERGY IN NUCLEI AND IN NUCLEAR MATTER

We discuss to what extent information on ground-state properties of finite nuclei (energies and radii) can be used to obtain constraints on the symmetry energy in nuclear matter and its dependence on the density. The starting point is a generalized Weizsäcker formula for ground-state energies. In particular effects from the Wigner energy and shell structure on the symmetry energy are investigated. Strong correlations in the parameter space prevent a clear isolation of the surface contribution. Use of neutron skin-information improves the situation. We find that inclusion of the Wigner effect leads to a larger value of the symmetry energy of nuclear matter at the saturation point.