The neutron drip line: single-particle degrees of freedom and pairing properties as sources of theoretical uncertainties

TL;DR

This paper investigates the main sources of theoretical uncertainties in predicting the two-neutron drip line using covariant density functional theory, highlighting the roles of single-particle energies and pairing properties.

Contribution

It identifies that differences in single-particle structures of covariant energy density functionals are the primary source of uncertainties, and suggests improvements in known nuclei can reduce these uncertainties.

Findings

Uncertainties are mainly due to differences in single-particle structure.

Uncertainties in known nuclei dominate the predictions.

Pairing properties have a secondary impact on drip line predictions.

Abstract

The sources of theoretical uncertainties in the prediction of the two-neutron drip line are analyzed in the framework of covariant density functional theory. We concentrate on single-particle and pairing properties as potential sources of these uncertainties. The major source of these uncertainties can be traced back to the differences in the underlying single-particle structure of the various covariant energy density functionals (CEDF). It is found that the uncertainties in the description of single-particle energies at the two-neutron drip line are dominated by those existing already in known nuclei. Only approximately one third of these uncertainties are due to the uncertainties in the isovector channel of CEDF's. Thus, improving the CEDF description of single-particle energies in known nuclei will also reduce the uncertainties in the prediction of the position of two-neutron drip line. The predictions of pairing properties in neutron rich nuclei depend on the CEDF. Although pairing properties affect moderately the position of the two-neutron drip line they represent only a secondary source for the uncertainties in the definition of the position of the two-neutron drip line.