Pole in k cotδ for doublet, s-wave, n-d scattering

The position of the pole in k cotδ, for doublet, s-wave, n-d scattering, and its residue are shown to be correlated with the doublet scattering length. An approximate, analytic solution of the ND equations of Barton and Phillips indicates a linear dependence on the doublet scattering length for the pole position, and a quadratic dependence for the residue. These relationships are tested by means of exact numerical solutions of ND equations and three-particle equations with separable two-particle interactions, and found to be qualitatively correct. The approximate, analytic solution of the ND equations leads to a formula for k cotδ, which is of the same form as the phenomenological formula used previously by other authors. A formalism is presented which makes it possible to parametrize the effect of the omitted portion of the left hand cut in an ND calculation. NUCLEAR REACTIONS Pole in n-d, doublet, s-wave k cotδ, ND calculations, solutions of three-particle equations with separable interactions.