Relativistic effects in the neutron-deuteron scattering lengths

We have estimated the contribution of relativistic effects to the neutron-deuteron scattering lengths by solving the nonrelativistic and relativistic Faddeev equations for several local and nonlocal potentials that act only in S waves. We found that the relativistic effects increase the quartet scattering length by about 0.2 fm and decrease the doublet scattering length by roughly the same amount. These effects are not small in the case of the doublet scattering length, where they represent a correction of more than 20% of the experimental value.