Isospin mixing in a particle-number conserving microscopic approach

TL;DR

This paper investigates isospin mixing in various nuclei using a particle-number conserving microscopic approach, highlighting the dominant role of pairing correlations over Coulomb effects in isospin symmetry breaking.

Contribution

The study implements the HTDA approach with Skyrme and delta interactions to analyze isospin mixing, emphasizing the impact of pairing correlations.

Findings

Pairing correlations significantly contribute to isospin-symmetry breaking.

Coulomb interaction has a lesser effect on isospin mixing.

Isospin-mixing parameters are similar for Tz=-1 and Tz=1, but larger for Tz=0 nuclei.

Abstract

We calculate the isospin-mixing parameter for several Tz=-1, Tz=0 and Tz=1 nuclei from Mg to Sn in the particle-number conserving Higher Tamm-Dancoff approach taking into account the pairing correlations. In particular we investigate the role of the Coulomb interaction and the |Tz|=1 pairing correlations. To do so the HTDA approach is implemented with the SIII Skyrme effective nucleon-nucleon interaction in the mean-field channel and a delta interaction in the pairing channel. We conclude from this investigation that the pairing correlations bring a large contribution to isospin-symmetry breaking, whereas the Coulomb interaction turns out to play a less important role. Moreover we find that the isospin-mixing parameters for Tz=-1 and Tz=1 nuclei are comparable while they are about twice as large for Tz=0 nuclei (between 3% and 6%, including doubly magic nuclei).