Abstract
Mirror energy differences (MEDs) and triplet energy differences (TEDs) in the analogue states are important probes of isospin-symmetry breaking. Inspired by the recent spectroscopic data of Se, we investigate these quantities for nuclei with large-scale shell-model calculations. For the first time, we find clear evidence suggesting that the isospin nonconserving (INC) nuclear force has a significant effect for the upper shell region. Detailed analysis shows that, in addition to the INC force, the electromagnetic spin-orbit interaction plays an important role for the large, negative MED in and 70 and the multipole Coulomb term contributes to the negative TED in all the triplet nuclei. The INC force and its strength needed to reproduce the experimental data are compared with those from the -matrix calculation using the modern charge-dependent nucleon-nucleon forces.
- Received 15 August 2013
- Revised 13 January 2014
DOI:https://doi.org/10.1103/PhysRevC.89.031302
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