By means of the process involving the capture of muons in ${\mathrm{O}}^{16}$ (g.s.) leading to definite final states in ${\mathrm{N}}^{16}$, we examine simultaneously (a) the quasiparticle model of nuclear structure developed by Migdal and (b) the pseudoscalar coupling generated by the axial-vector coupling in the effective weak-interaction Hamiltonian. In (a) we clarify the basic assumptions essential for the model and the connection between this model and other better-known (nuclear) models. In (b), it is shown that the Migdal model successfully eliminates the well-known discrepancy between theory and experiment in ${\mu }^{-}+{\mathrm{O}}^{16}\left(0^{+}\right)\to {\nu }_{\mu }+{\mathrm{N}}^{16}\left(2^{-}\right)$ and also in $e^{-}+{\mathrm{O}}^{16}\left(0^{+}\right)\to e^{-}+{\mathrm{O}}^{16*}\left(2^{-}\right)$. This in turn enables us to make use of the nuclear model to obtain a reasonable estimate of $C_P=\frac{m_{\mu }{F}_P}{F_A}$. The conclusion is that the one-pion-pole dominance hypothesis is compatible with all available data in ${\mathrm{O}}^{16}$ and that there seems to be no urgent need to introduce the tensor coupling as some people have suggested.

• Received 15 March 1967

DOI:https://doi.org/10.1103/PhysRev.161.955