It is shown that a drastic reduction of the ratio of the rates of the reactions ${}_{}{}^3{}_{}{}^{}\mathrm{He}$(${\mathrm{\pi }}^{\mathrm{-}}$,nn) and ${}_{}{}^3{}_{}{}^{}\mathrm{He}$(${\mathrm{\pi }}^{\mathrm{-}}$,np) for stopped pions is obtained once the effect of the short range two-nucleon components of the axial charge operator for the nuclear system is taken into account. In a calculation using simple wave functions but employing realistic models for the nucleon-nucleon interaction in the construction of these components of the axial charge operator, the predicted ratios can be brought to within 10–20 % of the empirical value.

• Received 4 May 1994

DOI:https://doi.org/10.1103/PhysRevC.50.2703