The Isobaric Triplets in the Nuclear 2p-shell and the Charge Independence of Nuclear Forces

Abstract

The positions of the lowest lying T=1 levels in the 2p-shell nuclei with T3=0 are calculated from the experimental positions of the ground states of the nuclei with T3= +1 and the energy differences between the ground states of the nuclei with T=½. Coulomb forces are considered as a perturbation in the shell model and it is shown that, apart from small terms which depend on symmetry, the method is equivalent to that used by Wilkinson (1956). The corrections due to symmetry are of the same order of magnitude as the significant differences which Wilkinson found between the experimental and the calculated positions of the T=1, T3=0 levels, and when these corrections are included the differences are no longer significant. The energy shift due to the charge dependence of nuclear forces caused by the pion mass difference is calculated and is shown to be appreciable. There is good agreement between theory and experiment for the isobars with A=14.