A six-quark dressed-bag description of np -> d \gamma radiative capture

Abstract

The radiative capture process $n p \to d \gamma$ is considered within the framework of a recently developed six-quark dressed-bag model for the nucleon-nucleon interaction. The calculations presented here include both the nucleon current and the meson-exchange current contributions. The latter uses short-range hadronic form factors for the pion exchange currents consistent with the soft cut-off parameter $\Lambda_{\pi NN}$ from the $NN$-potential. Contributions of the pion exchange current and $\Delta$-isobar current to the total cross section still cannot explain the discrepancy between the theoretical and experimental cross sections. Possibilities for new types of meson exchange currents associated with chiral fields inside multi-quark dressed-bag states in nuclei are discussed.