Elastic pion- He4 scattering

We have calculated differential cross sections for elastic ${\ensuremath{\pi}}^{+}$ and ${\ensuremath{\pi}}^{\ensuremath{-}}$ scattering from $^{4}\mathrm{He}$ at several incident pion energies from 24 to 110 MeV. A full multiple-scattering treatment incorporating all orders of scattering was used. A separable form for the pion-nucleon $t$ matrix having off-shell cutoff form factors was assumed. Inclusion of an effective angle transformation, which takes into account the motion of the struck nucleon, along with binding and recoil factors in the pion-nucleon amplitude, leads to good over-all agreement with the experimental data.NUCLEAR REACTIONS $^{4}\mathrm{He}({\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}},{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}})$ elastic scattering, $E=24\ensuremath{-}110$ MeV; multiple-scattering theory; separable pion-nucleon $t$ matrices, angle transformation; $\ensuremath{\sigma}(\ensuremath{\theta})$.