Two-pion exchange contributions to nuclear charge asymmetry

In a nonrelativistic formalism we derive a charge-symmetry-breaking (CSB) two-pion exchange interaction ${\mathit{V}}_{\mathit{nn}}$(2π)-${\mathit{V}}_{\mathit{pp}}$(2π), which includes both CSB vertex corrections and the CSB effect of propagators arising from the mass differences of the intermediate baryons in different charge states. While the former are small, the latter gives a contribution of the sign and scale comparable to the experimental difference in the effective range parameters and the binding energy difference between ${}_{}{}^3{}_{}{}^{}\mathrm{H}$ and ${}_{}{}^3{}_{}{}^{}\mathrm{He}$. © 1996 The American Physical Society.