Nucleon polarization in three-body models of polarizedLi6

Just as ${}_{}{}^3{}_{}{}^{}\to$ can be approximately characterized as a polarized neutron target, polarized ${}_{}{}^6{}_{}{}^{}\mathrm{LiD}$ has been advocated as a good isoscalar nuclear target for the extraction of the polarized gluon content of the nucleon. The original argument rests upon a presumed ‘‘alpha + deuteron’’ picture of ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$, with the polarization of the nucleus carried by the polarization of the deuteron. We have calculated the polarization of the constituents of ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ as a three-body bound state of α+n+p interacting with local potentials fitted to the scattering data. It is necessary to include partial waves up to j=17/2 (75 channels, or, when including the T=1 state, 150 channels) in the Faddeev equations before the energy eigenvalue converges. The longitudinal form factors are then described well by the wave function. Various combinations of αN and NN strong and Coulomb potentials yield a straight line in the charge radius vs energy plane which, unlike those of previous calculations, passes through the experimental datum. We find for all cases a polarization of the valence neutron in excess of 90%. This may make polarized ${}_{}{}^6{}_{}{}^{}\mathrm{LiD}$ an attractive target for many nuclear physics purposes, since its neutrons are effectively 45% polarized.