Isospin nonconserving interaction in the T=1 analogue states of the mass-70 region

Abstract

Mirror energy differences (MED) and triplet energy differences (TED) in the T=1 analogue states are important probes of isospin-symmetry breaking. Inspired by the recent spectroscopic data of 66Se, we investigate these quantities for A=66-78 nuclei with large-scale shell-model calculations. For the first time, we find clear evidences suggesting that the isospin nonconserving (INC) nuclear force has a significant effect for the upper fp 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 A=66 and 70 and the multipole Coulomb term contributes to the negative TED in all the T=1 triplet nuclei. The INC force and its strength needed to reproduce the experimental data are compared with those from the G-matrix calculation using the modern charge-dependent nucleon-nucleon forces.

5 pages, 5 figures, accepted in Phys. Rev. C

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• Low-momentum interactions with smooth cutoffs
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• Phase transition in exotic nuclei along the $N=Z$ line
• Observation of mutually enhanced collectivity in self-conjugate ${}_{38}^{76}$Sr${}_{38}$
• Coulomb shifts and shape changes in the mass 70 region
• Isospin symmetry breaking at high spins in the mirror pair 67Se and 67As
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Cited by in corpus (5)

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• Effects of Coulomb and isospin symmetry breaking interactions on neutron-skin thickness
• Shell model analysis of the $B(E2,2^{+}\to 0^{+})$'s in the A=70 T=1 triplet
• Mirror energy differences in T=1/2 f7/2-shell nuclei within isospin-dependent DFT
• Exploring isospin-nonconserving effects in the upper $fp$ shell with new mass measurements