Charge symmetry breaking inNNscattering with an interaction from effective field theory

The effect of isospin breaking pion s-wave rescattering is included in elastic $\mathrm{NN}$ scattering at low energies using an interaction obtained from effective field theory. Although this mechanism gave a large contribution to charge symmetry breaking in $n\overrightarrow{p}d{\pi }^0,$ the effect is rather small in $\mathrm{pp}$ vs $\mathrm{nn}$ scattering parameters and in the ${}^3\mathrm{H}{-}^3\mathrm{He}$ binding energy difference. This smallness is caused by large cancellation of the up-down quark mass difference contribution and electromagnetic effects to the $\mathrm{np}$ mass difference.