Ndzero-energy scattering

Faddeev-type configuration-space three-body scattering equations are solved for selected two-body- and two-body-plus-three-body-potential model Hamiltonians to obtain absolute predictions for the nucleon-deuteron scattering lengths ${}_{}{}^2{}_{}{}^{}$ ${\mathit{a}}_{\mathit{n}\mathit{d}}$,${}^4$ ${\mathit{a}}_{\mathit{n}\mathit{d}}$, ${}_{}{}^2{}_{}{}^{}$ ${\mathit{a}}_{\mathit{p}\mathit{d}}$, and ${}_{}{}^4{}_{}{}^{}$ ${\mathit{a}}_{\mathit{p}\mathit{d}}$. Convergence for these zero-energy scattering parameters as a function of the number of NN-potential partial waves included in the calculation is attained for the first time. Kohn variational estimates provide a measure of the precision of our numerical results. The nd predictions agree well with the measured values. The pd predictions differ substantially from accepted experimental values which are extrapolated from measurements made above 400 keV.