Reaction ${\mathrm{Li}}^6({\pi }^{+},pp){\mathrm{He}}^4$ and $T=1\mathrm{}$ States in ${\mathrm{He}}^4$

An analysis of the reaction ${\mathrm{Li}}^6({\pi }^{+},pp){\mathrm{He}}^4$ shows that the mechanism for transitions to the ground and excited states in ${\mathrm{He}}^4$ is dominated by a single-pole model when the momentum transfer is restricted to small values. Preferential excitation of the $T=1\mathrm{}$ levels in ${\mathrm{He}}^4$ is observed and is explained on the basis of the single-pole model.