A finite range pairing force for density functional theory in superfluid nuclei

TL;DR

This paper introduces a finite-range, separable pairing force for density functional theory in superfluid nuclei, simplifying calculations while accurately capturing pairing correlations in both nuclear matter and finite nuclei.

Contribution

It develops a separable pairing force that preserves translational invariance and finite range, avoiding cut-off issues, and demonstrates its effectiveness in relativistic Hartree-Bogoliubov calculations.

Findings

Accurately reproduces pairing properties in nuclear matter and finite nuclei.

Simplifies calculations by avoiding cut-off problems of zero-range forces.

Applicable to nuclei far from stability and beyond mean-field approaches.

Abstract

The problem of pairing in the $^{1}$S$_{0}$ channel of finite nuclei is revisited. In nuclear matter forces of separable form can be adjusted to the bare nuclear force, to any phenomenological pairing interaction such as the Gogny force or to exact solutions of the gap equation. In finite nuclei, because of translational invariance, such forces are no longer separable. Using well known techniques of Talmi and Moshinsky we expand the matrix elements in a series of separable terms, which converges quickly preserving translational invariance and finite range. In this way the complicated problem of a cut-off at large momenta or energies inherent in other separable or zero range pairing forces is avoided. Applications in the framework of the relativistic Hartree Bogoliubov approach show that the pairing properties are depicted on almost the same footing as by the original pairing interaction not only in nuclear matter, but also in finite nuclei. This simple separable force can be easily applied for the investigation of pairing properties in nuclei far from stability as well as for further investigations going beyond mean field theory.