Covariant density functional theory: The role of the pion

TL;DR

This paper explores the impact of including pions in Covariant Density Functional Theory, showing they do not compromise bulk properties but influence single particle energies and nuclear binding.

Contribution

It introduces a pion coupling in Covariant Density Functional Theory within the relativistic Hartree-Fock framework, highlighting effects on nuclear structure.

Findings

Pions can be incorporated without disrupting bulk nuclear properties.

Pion tensor coupling affects single particle energies.

Pion inclusion influences binding energies of specific nuclei.

Abstract

We investigate the role of the pion in Covariant Density Functional Theory. Starting from conventional Relativistic Mean Field (RMF) theory with a non-linear coupling of the $\sigma$-meson and without exchange terms we add pions with a pseudo-vector coupling to the nucleons in relativistic Hartree-Fock approximation. In order to take into account the change of the pion field in the nuclear medium the effective coupling constant of the pion is treated as a free parameter. It is found that the inclusion of the pion to this sort of density functionals does not destroy the overall description of the bulk properties by RMF. On the other hand, the non-central contribution of the pion (tensor coupling) does have effects on single particle energies and on binding energies of certain nuclei.