Exchange Effects in Radiativen−pCapture

The contribution of the one-pion-exchange interaction current to the transition amplitude for radiative $n-p$ capture at thermal energies is evaluated using the Chew-Low static model for the amplitude for photoproduction of pions off nucleons. A correct treatment of the pion-rescattering term in that amplitude gives essential agreement with the static-quark-model calculation of Riska and Brown which considers only nucleon excitation to the $\Delta \mathrm{}\left(1236\right)\mathrm{}$ state.