Radiative Muon Capture in Calcium

Abstract

The branching ratio relative to ordinary muon capture and the photon asymmetry relative to the muon-spin direction were measured for radiative muon capture in $^{40}\mathrm{Ca}$. For ~ 1200 photon events, the partial branching ratio is ${R}_{k>57 \mathrm{MeV}}=(21.1\ifmmode\pm\else\textpm\fi{}1.4)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$, and the asymmetry for $k>63.5$ MeV is +0.90\ifmmode\pm\else\textpm\fi{}0.50. A fit of the photon spectrum to the theory of Rood, Yano, and Yano gives the value ${{g}_{P}}^{\ensuremath{\mu}}=(6.5\ifmmode\pm\else\textpm\fi{}1.6){g}_{A}$ for the pseudoscalar-coupling constant. These results are in disagreement with earlier experiments.