Description of the Low-Energy Doublet Neutron-Deuteron Scattering on the Basis of the Triton Bound and Virtual State Parameters

Low-energy doublet neutron-deuteron scattering is described on the basis of the triton bound and virtual state parameters - the energies and the nuclear vertex constants of these states. The van Oers-Seagrave formula is derived from the Bargmann representation of the S matrix for a system having two states. The presence of a pole in this formula is shown to be a direct corollary of the existence of a low-energy triton virtual state. Simple explicit expressions for the nd scattering length and for the pole of the function $k\cot \delta $ are obtained in terms of the triton bound and virtual state parameters. Numerical calculations of the nd low-energy scattering parameters show their high sensitivity to variations in the asymptotic normalization constant of the virtual state $C_{v}^{2}$. The $C_{v}^{2}$ value fitted in our model to the experimental result for the nd scattering length is $C_{v}^{2}=0.0592$.