Simple Model for Corrections to the Isobaric Multiplet Mass Equation

A simple nonperturbative model is used to estimate corrections to the first-order perturbation-theory formula for the isobaric multiplet masses. The leading-order correction to the equation, which is proportional to $T_z^{}{}_{}{}^3$, is found to be much smaller than expected from second-order perturbation arguments and from limits set by experiments.