Meson-exchange currents and energetic particle emission from μ − capture

Abstract

We consider corrections to the impulse approximation calculation of the excitation function generated by muon capture in complex nuclei, in the form of captures on pairs of nucleons induced via meson-exchange currents. Within the Fermi gas model for the nucleus, these multinucleon captures are found to account for 4–8% of the experimental muon capture rates and to produce high excitation energies. The emission of pre-equilibrium protons with energies between 40 and 90 MeV is calculated for several nuclei using the hybrid exciton model. The agreement with experiment on emission spectra and rates is generally good. The emission of neutrons at these energies is also discussed.