EFFECTS OF SHORT-RANGE DELTA-N INTERACTION ON OBSERVABLES OF THE PI-NN SYSTEM

The inadequacy of standard few-body approaches in describing the NN system has motivated searches for the responsible missing mechanism. In the case of d scattering, it has recently been asserted that an additional short range N interaction can account for essentially all the discrepancies between a few-body calculation and experimental data. This conclusion, however, has been based on calculations where a phenomenological N interaction is added only in Born term to background few-body amplitudes. In the present work we investigate the effect of including such a N interaction to all orders within a unitary few-body calculation of the NN system. Besides testing the validity of adding the N interaction in Born term in d scattering, our fully coupled approach also enables us to see the influence of the same N interaction on the processes NNd and NN'NN. For d elastic scattering, we find that the higher order N interaction terms can have as much influence on d observables as the lowest order contribution alone. Moreover, we find that the higher order contributions tend to cancel the effect obtained by adding the N interaction in Born term only. The effect of the same N interaction on NN'd and NN'NN appears to be as significant as in d'd, suggesting that future investigations of the short range N interaction should be done in the context of the fully coupled NN system. © 1990 The American Physical Society.