The induced pseudoscalar interaction and the μ-capture in He³

Abstract

Recent measurements ofμ-capture in He³ as well as the determination of the electric and magnetic formfactors of He³ and H³ allow a detailed analysis of theμ-capture process in He³. Assuming only the theory of a conserved vector current these experiments can be used to derive a relation for the axial vector part of the He³→H³ transition amplitude. This result is compared with a nuclear physics calculation of the formfactors. It follows that the induced pseudoscalar coupling constant for the muon capture on a free proton has a sign in agreement with the value predicted byGoldberger andTreiman. Its magnitude seems to be somewhat larger than the predicted value. We also find qualitative agreement with an extension ofNambu's idea of an almost conserved axial vector current to the case of the He³→H³ transition.