Charge asymmetry in non-relativistic nucleon-nucleon potential derived from charge symmetric relativistic interaction

Consider a relativistic model of the nucleon-nucleon (NN) system subject to an interaction which is a sum of a charge symmetric NN interaction and the Coulomb potential. When the model is rewritten in the form of a non-relativistic model, the resulting effective non-relativistic potential obtains a charge-symmetry-breaking (CSB) component. We illustrate this by means of the Breit equation. If the relativistic NN interaction contains a combination of a strongly attractive Lorentz scalar and a strongly repulsive vector, the non-relativistic potential obtains a large CSB component. When the magnetic interaction is included, however, the CSB effect may be reduced. This and other aspects, in which relativistic and non-relativistic models may exhibit significant differences, are discussed. (author)