Abstract
The quadratic form of the isobaric multiplet mass equation (IMME), which was originally suggested by Wigner and has been generally regarded as valid, is seriously questioned by recent high-precision nuclear mass measurements. The usual resolution to this problem is to add empirically the cubic and quartic terms to characterize the deviations from the IMME, but finding the origin of these terms remains an unsolved difficulty. Based on a strategy beyond Wigner's first-order perturbation, we derive explicitly the cubic and quartic terms. These terms are shown to be generated by the effective charge-symmetry-breaking and charge-independence-breaking interactions in the nuclear medium combined with the Coulomb polarization effect. Calculations for the and lower shells explore a systematic emergence of the cubic term, suggesting a general deviation from the original IMME. Intriguingly, the magnitude of the deviation exhibits an oscillation-like behavior with mass number, modulated by the shell effect.
- Received 19 September 2018
DOI:https://doi.org/10.1103/PhysRevC.99.014319
©2019 American Physical Society