Isospin symmetry breaking in the mirror pair $^{73}$Sr-$^{73}$Br

TL;DR

This paper investigates isospin symmetry breaking in the mirror nuclei $^{73}$Sr and $^{73}$Br using large-scale shell model calculations, highlighting the dominant role of Coulomb interactions and estimating nuclear contributions.

Contribution

It provides a detailed theoretical analysis of ISB effects in $^{73}$Sr-$^{73}$Br, incorporating large valence space and effective interactions to match experimental observations.

Findings

Calculated shifts align with experimental inversion of states.

Coulomb interaction is identified as the dominant ISB source.

Nuclear ISB contribution estimated at approximately 25 keV.

Abstract

The recent experimental observation of isospin symmetry breaking (ISB) in the ground states of the $T=3/2$ mirror pair $^{73}$Sr - $^{73}$Br is theoretically studied using large-scale shell model calculations. The large valence space and the successful PFSDG-U effective interaction used for the nuclear part of the problem capture possible structural changes and provide a robust basis to treat the ISB effects of both electromagnetic and non-electromagnetic origin. The calculated shifts and mirror-energy-differences are consistent with the inversion of the $I^{\pi}$= 1/2$^{-}, 5/2^{-}$ states between $^{73}$Sr - $^{73}$Br, and suggest that the role played by the Coulomb interaction is dominant. An isospin breaking contribution of nuclear origin is estimated to be $\approx 25$ keV.