Radiative Pion Capture and the Pion-Nucleus Vertex Function

Abstract

We use the Kroll-Ruderman theorem and the elementary-particle treatment of the nucleus to calculate $s$-wave capture rate of pions by ${\mathrm{He}}^{3}$ and ${\mathrm{Li}}^{6}$. The results are compared with previous estimates and experiment. We also use the observed Panofsky ratio to study the $\ensuremath{\pi}{\mathrm{He}}^{3}{\mathrm{H}}^{3}$ vertex function.