Charge-symmetry breaking and n-n scattering lengths

Recent experimental and theoretical investigations of ρ-ω and η-π mixing have caused us to re-examine the effects of these mixings on the charge-symmetry breaking of nuclear forces. The charge asymmetry of the nucleon-nucleon force in the singlet S-state is used to predict the n-n scattering length in terms of the measured p-p one. The extra attraction of the n-n potential in the ¹S₀ state gives rise to a change of roughly −0.8 fm in the corresponding scattering length. The magnitude (and sign) of the charge asymmetry is approximately that required to understand the binding-energy differences of the mirror nuclei ³He-³H and ⁴¹Sc-⁴¹Ca.