Isospin mixing of isospin-projected Slater determinants: formalism and preliminary applications

TL;DR

This paper introduces a new theoretical method for isospin projection of Slater determinants, enabling detailed analysis of isospin mixing in N=Z nuclei and addressing issues of spurious symmetry breaking.

Contribution

It develops a novel formalism for isospin projection and applies it to study isospin mixing, highlighting the impact of basis size and unphysical contributions.

Findings

Isospin mixing in N=Z nuclei can be quantified with the new method.

Spurious isospin-symmetry breaking can contribute up to 30% to the mixing.

The basis size influences the calculated isospin mixing values.

Abstract

We report on the development of a new theoretical tool that allows for isospin projection of Slater determinants and we present its first applications. In particular, we determine the isospin mixing in ground states of N=Z nuclei and discuss its dependence on the size of the harmonic-oscillator basis used in the calculations. We also discuss the unphysical contribution to the isospin mixing caused by the spurious isospin-symmetry breaking inherent to the mean-field approach. We show that these contributions may be as large as 30% of the value of the isospin-mixing parameter.