Nuclear muon capture by 3He: Meson exchange currents for the triton channel.

Abstract

We have calculated exchange corrections for nuclear muon capture by $^{3}\mathrm{He}$ leading to the $^{3}\mathrm{H}$ final state using the hard-pion model and realistic nuclear wave functions. These currents modify the vector and axial part of the weak nuclear current. In their absence the rate is 12% smaller than found by experiment. Our final result for the rate is 1502\ifmmode\pm\else\textpm\fi{}32 per second. For the analyzing powers we find ${\mathit{A}}_{\mathit{v}}$=0.515\ifmmode\pm\else\textpm\fi{}0.005, ${\mathit{A}}_{\mathit{t}}$=-0.375\ifmmode\pm\else\textpm\fi{}0.004, and ${\mathit{A}}_{\mathrm{\ensuremath{\Delta}}}$=-0.110\ifmmode\pm\else\textpm\fi{}0.006. These predictions use the PCAC value of ${\mathit{g}}_{\mathit{P}}$. The variation of the observables with ${\mathit{g}}_{\mathit{P}}$ is also reported. \textcopyright{} 1996 The American Physical Society.