Meson mixing and the charge asymmetry of the NN interaction

Electromagnetic mixing of isospin eigenstates for the neutral mesons leads to charge-asymmetry effects in the NN interaction. This is discussed in terms of a single-meson-exchange model in which the coupling constants are taken from SU3 and from phenomenological estimates. Mixing of the vector mesons is considerably more important here than mixing of the pseudoscalar mesons. The difference (ann − app) between scattering lengths for the strong n-n and p-p interactions could be about −1.5 fm, when the n-p mass difference (which contributes about −0.5 fm) is also considered. Other charge-asymmetry effects which have been estimated are much smaller.