arXiv subjects

Karim Bennaceur

Publications and source records attributed to Karim Bennaceur.

6 recordsLinked to original sources

arXiv2026

Semi-regularised three-body pseudopotential for mean-field and beyond-mean-field calculations

We derive the most general form of a local leading-order semi-regularised three-body pseudopotential. This particular form of pseudopotential is developed with the aim of generating contributions to the nuclear energy density functional (EDF) in both the particle-hole and particle-particle channels and, hence, to be usable in mean-field and beyond-mean-field calculations without ambiguities or mathematical difficulties. Once the EDF is obtained, analytical expressions of commonly considered properties of infinite nuclear matter are provided. Finally, the structure of the EDF and the associated mean fields are given for spherically-symmetric systems.

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arXiv2026

Parameter adjustment of nuclear leading-order local pairing energy density functionals

(See paper for full abstract) This study reports on the benchmarking of a protocol for the adjustment of the parameters of a local leading-order (LO) T=1 (like-particle) pairing EDF that consists in adjusting the density-dependence of the 1S0 pairing gap at the chemical potential in infinite nuclear matter (INM). When using a suitably chosen reference calculation, this protocol leads to consistent results for the odd-even staggering of masses of spherical and heavy deformed nuclei and also for the rotational moments of inertia calculated in a time-reversal-breaking cranked HFB approach. The implementation of the HFB solver for infinite matter at arbitrary isospin asymmetry used for this study is sketched in appendices. Additional points that are discussed concern (i) the illustration that the gaps at the chemical potential are not necessarily sufficient to completely characterise the pairing interaction in infinite matter, and that adjusting LO pairing EDF to reproduce gaps obtained from finite-range pairing interactions in HFB or from more microscopic calculations can lead to unrealistic predictions for finite nuclei; (ii) the finding that some regions of the parameter space for the density dependence of the T=1 LO pairing EDF lead to a spurious transition to a Bose-Einstein condensate of di-nucleons in spite of producing realistic pairing correlations for well-bound nuclei; (iii) the correlation between effective mass and the parameters of the LO pairing EDF that control the form factor of the density dependence when reproducing pairing gaps in infinite matter, (iv) the significant impact on the odd-even staggering of masses made by either including or not the spin-gradient terms in the particle-hole part of the Skyrme EDF; (v) the sizeable impact of keeping or not the contribution from the density-dependent LO pairing EDF to the mean fields on the odd-even staggering of radii.

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arXiv2024

Impact of choices for center-of-mass correction energy on the surface energy of Skyrme energy density functionals

In the framework of nuclear energy density functional (EDF) methods, many nuclear phenomena can be related to the deformation of intrinsic states. Their accurate modeling relies on the correct description of the change of nuclear binding energy with deformation. The two most important contributions to the deformation energy have their origin in shell effects and the surface energy coefficient of nuclear matter. In a first step, we build nine series of parametrizations with a systematically varied surface-energy coefficient a_surf for three frequently-used options for the CM correction (none, one-body term only, full one-body and two-body contributions) combined with three values for the isoscalar effective mass m^*_0/m (0.7, 0.8, 0.85) and analyse how well each of these parametrizations can be adjusted to the properties of spherical nuclei and infinite nuclear matter. In a second step, we performed additional fits without the constraint on surface energy, adding one ``best-fit" parametrization to each of the nine series. We then benchmark these parametrizations to the deformation properties of heavy nuclei by means of three-dimensional Hartree-Fock-Bogoliubov calculations that allow for non-axial and/or non-reflection symmetric configurations. We perform a detailed correlation analysis between surface and volume properties of nuclear matter using the nine series of parametrizations. The best fits out of each series are then benchmarked on the fission barriers of Pu240 and Hg180, as well as on the properties of deformed states at normal and superdeformation for actinides and nuclei in the neutron-deficient Hg region. (see paper for full abstract)

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arXiv2016

Landau parameters for energy density functionals generated by local finite-range pseudopotentials

In Landau theory of Fermi liquids, the particle-hole interaction near the Fermi energy in different spin-isospin channels is probed in terms of an expansion over the Legendre polynomials. This provides a useful and efficient way to constrain properties of nuclear energy density functionals in symmetric nuclear matter and finite nuclei. In this study, we present general expressions for Landau parameters corresponding to a two-body central local regularized pseudopotential. We also show results obtained for two recently adjusted NLO and N$^2$LO parametrizations. Such pseudopotentials will be used to determine mean-field and beyond-mean-field properties of paired nuclei across the entire nuclear chart.

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arXiv2014

Semi-contact 3-body interaction for nuclear density functional theory

To solve difficulties related to the use of nuclear density functional theory applied in its beyond mean-field version, we introduce a semi-contact 3-body effective interaction. We show that this interaction is a good candidate to replace the widely used density dependent effective interaction. The resulting new functionals are able to describe symmetric, neutron, polarized and neutron polarized nuclear matter as well as the effective mass properties simultaneously.

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arXiv2007

The Tensor Part of the Skyrme Energy Density Functional

We systematically study the effect of the J^2 tensor terms in the Skyrme energy functional on properties of spherical nuclei. We build a set of 36 parameterizations covering a wide range of the corresponding parameter space. We analyze the impact of the tensor terms on the evolution of single-particle-level splittings along chains of semi-magic nuclei in spherical calculations. We find that positive values of the coupling constants of proton-neutron and like-particle tensor terms allow for a qualitative description of the evolution of neutron and proton single-particle level splittings in chains of Ca, Ni and Sn isotopes.

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