Asymmetries for elastic scattering of pi + from polarized 3He and the Delta -neutron spin-spin interaction.

Abstract

Asymmetries for ${\ensuremath{\pi}}^{+}$ elastic scattering from polarized ${}^{3}\mathrm{He}$ were measured across the $\ensuremath{\Delta}$(1232) $\ensuremath{\pi}$-nucleon resonance region at incident energies ${T}_{\ensuremath{\pi}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}142$, 180, and 256 MeV. Large discrepancies were found between the data and calculations that use the multiple scattering formalism and Faddeev wave functions. Inclusion of a $\ensuremath{\Delta}$-neutron spin-spin interaction term in the calculations gives a greatly improved representation of the data.