Isospin mixing in nuclei around N=Z and the superallowed beta-decay

TL;DR

This paper develops an isospin-projection method within the Skyrme-DFT framework to accurately evaluate isospin mixing and its impact on superallowed beta-decay in N≈Z nuclei.

Contribution

The authors introduce a novel isospin-projection scheme on top of Skyrme-DFT, enabling consistent treatment of isospin mixing in nuclear states.

Findings

Quantified isospin impurities in ground states of N≈Z nuclei.

Calculated isospin-breaking corrections to superallowed beta-decay.

Demonstrated the importance of combined isospin and angular-momentum projection.

Abstract

Theoretical approaches that use one-body densities as dynamical variables, such as Hartree-Fock or the density functional theory (DFT), break isospin symmetry both explicitly, by virtue of charge-dependent interactions, and spontaneously. To restore the spontaneously broken isospin symmetry, we implemented the isospin-projection scheme on top of the Skyrme-DFT approach. This development allows for consistent treatment of isospin mixing in both ground and exited nuclear states. In this study, we apply this method to evaluate the isospin impurities in ground states of even-even and odd-odd N~Z nuclei. By including simultaneous isospin and angular-momentum projection, we compute the isospin-breaking corrections to the 0+ --> 0+ superallowed beta-decay.