arXiv subjects

S. Marcos

Publications and source records attributed to S. Marcos.

5 recordsLinked to original sources

arXiv2026

Charge radii of Sn isotopes in the relativistic mean field approximation

The kink observed in the nuclear charge radius of Sn isotopes around neutron number $N = 82$ is investigated within the relativistic mean-field (RMF) framework using the NL3$^*$ parameter set. It is shown that the small components of the Dirac spinors for the neutron single-particle states near the Fermi level play a crucial role in forming the kink through their contribution to the proton central potential. In particular, the significant differences between the radial parts of the small components of spin-orbit partner states make neutrons with $j = l - 1/2$ more efficient in increasing the nuclear charge radius than those with $j = l + 1/2$. However, the effect induced by the small components alone does not fully account for the magnitude of the kink observed in Sn isotopes.

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arXiv2003

Description of nuclear systems within the relativistic Hartree-Fock method with zero range self-interactions of the scalar field

An exact method is suggested to treat the nonlinear self-interactions (NLSI) in the relativistic Hartree-Fock (RHF) approach for nuclear systems. We consider here the NLSI constructed from the relativistic scalar nucleon densities and including products of six and eight fermion fields. This type of NLSI corresponds to the zero range limit of the standard cubic and quartic self-interactions of the scalar field. The method to treat the NLSI uses the Fierz transformation, which enables one to express the exchange (Fock) components in terms of the direct (Hartree) ones. The method is applied to nuclear matter and finite nuclei. It is shown that, in the RHF formalism, the NLSI, which are explicitly isovector-independent, generate scalar, vector and tensor nucleon self-energies strongly density-dependent. This strong isovector structure of the self-energies is due to the exchange terms of the RHF method. Calculations are carried out with a parametrization containing five free parameters. The model allows a description of both types of systems compatible with experimental data.

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arXiv2000

On the relativistic origin of the kink effect in the chain of Pb isotopes

We investigate the origin of the kink effect (KE) in the relativistic mean field theory by transforming the single-particle Dirac equation into a Schrodinger-like equation. It is found that relativistic self-consistent effects as well as contributions from the rho meson determine the actual structure of the KE. However, the spin-orbit force generated by the rho meson has no significant influence on the KE.

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arXiv2000

Spin-Orbit Splitting in Non-Relativistic and Relativistic Self-Consistent Models

The splitting of single-particle energies between spin-orbit partners in nuclei is examined in the framework of different self-consistent approachs, non-relativistic as well as relativistic. Analytical expressions of spin-orbit potentials are given for various cases. Proton spin-orbit splittings are calculated along some isotopic chains (O, Ca, Sn) and they are compared with existing data. It is found that the isotopic dependence of the relativistic mean field predictions is similar to that of some Skyrme forces while the relativistic Hartree-Fock approach leads to a very different dependence due to the strong non-locality.

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arXiv1997

On the binding energy of double Λhypernuclei in the relativistic mean field theory

We calculate the binding energy of two $Λ$ hyperons bound to a nuclear core within the relativistic mean field theory. The starting point is a two-body relativistic equation of the Breit type suggested by the RMFT, and corrected for the two-particle interaction. We evaluate the 2 $Λ$ correlation energy and estimate the contribution of the $σ^*$ and $Φ$ mesons, acting solely between hyperons, to the bond energy $Δ{B_{ΛΛ}}$ of $^6_{ΛΛ}He$, $^{10}_{ΛΛ}Be$ and $^{13}_{ΛΛ}B$. Predictions of the $Δ{B_{ΛΛ}}$ A dependence are made for heavier $Λ$-hypernuclei.

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