25 research outputs found
Skyrme functional with tensor terms from \textit{ab initio} calculations of neutron-proton drops
A new Skyrme functional devised to account well for standard nuclear
properties as well as for spin and spin-isospin properties is presented. The
main novelty of this work relies on the introduction of tensor terms guided by
\textit{ab initio} relativistic Brueckner-Hartree-Fock calculations of
neutron-proton drops. The inclusion of tensor term does not decrease the
accuracy in describing bulk properties of nuclei, experimental data of some
selected spherical nuclei such as binding energies, charge radii, and
spin-orbit splittings can be well fitted. The new functional is applied to the
investigation of various collective excitations such as the Giant Monopole
Resonance (GMR), the Isovector Giant Dipole Resonance (IVGDR), the Gamow-Teller
Resonance (GTR), and the Spin-Dipole Resonance (SDR). The overall description
with the new functional is satisfactory and the tensor terms are shown to be
important particularly for the improvement of the Spin-Dipole Resonance
results. Predictions for the neutron skin thickness based on the non-energy
weighted sum rule of the Spin-Dipole Resonance are also given.Comment: 16 pages, 12 figure
Effects of tensor forces in nuclear spin-orbit splittings from ab initio calculations
A systematic and specific pattern due to the effects of the tensor forces is
found in the evolution of spin-orbit splittings in neutron drops. This result
is obtained from relativistic Brueckner-Hartree-Fock theory using the bare
nucleon-nucleon interaction. It forms an important guide for future microscopic
derivations of relativistic and nonrelativistic nuclear energy density
functionals.Comment: 14 pages, 3 figure
Relativistic Brueckner-Hartree-Fock theory for neutron drops
Neutron drops confined in an external field are studied in the framework of
relativistic Brueckner-Hartree-Fock theory using the bare nucleon-nucleon
interaction. The ground state energies and radii of neutron drops with even
numbers from to are calculated and compared with results
obtained from other nonrelativistic \textit{ab initio} calculations and from
relativistic density functional theory. Special attention has been paid to the
magic numbers and to the sub-shell closures. The single-particle energies are
investigated and the monopole effect of the tensor force on the evolutions of
the spin-orbit and the pseudospin-orbit splittings is discussed. The results
provide interesting insight of neutron rich systems and can form an important
guide for future density functionals.Comment: 31 pages, 12 figure
Fully self-consistent relativistic Brueckner-Hartree-Fock theory for finite nuclei
Starting from the relativistic form of the Bonn potential as a bare
nucleon-nucleon interaction, the full Relativistic Brueckner-Hartree-Fock
(RBHF) equations are solved for finite nuclei in a fully self-consistent basis.
This provides a relativistic ab initio calculation of the ground state
properties of finite nuclei without any free parameters and without three-body
forces. The convergence properties for the solutions of these coupled equations
are discussed in detail at the example of the nucleus O. The binding
energies, radii, and spin-orbit splittings of the doubly magic nuclei He,
O, and Ca are calculated and compared with the earlier RBHF
calculated results in a fixed Dirac Woods-Saxon basis and other
non-relativistic ab initio calculated results based on pure two-body forces.Comment: 22 pages, 13 figure
Particle-vibration coupling for giant resonances beyond the diagonal approximation
A self-consistent particle-vibration coupling (PVC) model without diagonal
approximation is presented. The diagonal approximation, that neglects
completely the interaction between the doorway states, has been removed by
taking into account the interaction between the two particle-holes inside the
doorway states. As applications, isoscalar giant monopole, dipole, and
quadrupole resonances in 16O are investigated based on the use of Skyrme
functionals. The diagonal approximation is found to clearly impact the strength
distribution of the giant quadrupole resonance, and the description of the
experimental data is improved without this approximation. The impact of the
diagonal approximation is analyzed in detail, especially its effect on the
eigenenergies and the induced coupling between neutron and proton particle-hole
configurations. The latter is a direct and physically sound effect of the
improvement on our formalism. The importance of using self-consistently the
full effective interaction in the PVC vertex, and the effect of its
renormalization via the subtraction method, are also discussed. For
completeness, we also analyze the dependence of our results on the Skyrme
parametrization.Comment: 22 pages, 18 figure
Pseudospin symmetry: Recent progress with supersymmetric quantum mechanics
It is an interesting and open problem to trace the origin of the pseudospin
symmetry in nuclear single-particle spectra and its symmetry breaking mechanism
in actual nuclei. In this report, we mainly focus on our recent progress on
this topic by combining the similarity renormalization group technique,
supersymmetric quantum mechanics, and perturbation theory. We found that it is
a promising direction to understand the pseudospin symmetry in a quantitative
way.Comment: 4 pages, 1 figure, Proceedings of the XX International School on
Nuclear Physics, Neutron Physics and Applications, Varna, Bulgaria, 16-22
September, 201
Ab initio calculation of the alpha-particle monopole transition form factor: No puzzle for nuclear forces
We present a parameter-free ab initio calculation of the -particle
monopole transition form factor in the framework of nuclear lattice effective
field theory. We use a minimal nuclear interaction that was previously used to
reproduce the ground state properties of light nuclei, medium-mass nuclei, and
neutron matter simultaneously with no more than a few percent error in the
energies and charge radii. The results for the monopole transition form factor
are in good agreement with recent precision data from Mainz.Comment: 5 pages, 3 figure