Correlations between observables in n-d scattering

We have found in the neutron-deuteron scattering a correlation of $Kcot{}_{}{}^2{}_{}{}^{}\delta _0^{}{}_{}{}^{}$ with the doublet scattering length (${}_{}{}^2{}_{}{}^{}a$) which is roughly linear for energies above the threshold. We predict the value of $Kcot{}_{}{}^2{}_{}{}^{}\delta _0^{}{}_{}{}^{}$ for the accepted experimental ${}_{}{}^2{}_{}{}^{}a$ value at the energies of 5.6 and 9.4 MeV. Our calculations reproduce the ${}_{}{}^2{}_{}{}^{}\delta _0^{}{}_{}{}^{}$ p-d experimental data of Arvieux, but are in disagreement with the experimental n-d ${}_{}{}^2{}_{}{}^{}\delta _0^{}{}_{}{}^{}$ data of Van Oers and Seagrave.