Radiative Pion Capture and Muon Capture in Three-Nucleon Systems

Abstract

Radiative pion capture and muon capture in nuclei can be studied using two methods, the elementary particle method (EPM) and the impulse approximation method (IAM). The EPM is fully relativistic and incorporates the effects due to virtual mesons and baryon resonances within nuclei. The structure of the nuclei are described by form factors which are partially determined by electron scattering and β decay data. Unlike the EPM, the IAM can be applied to a variety of muon and pion capture reactions. In this method the nuclear structure is described by non-relativistic wave functions and the interaction of the nucleus is expressed in terms of the interaction of the constituent nucleons. Meson and baryon resonance effects are not included. Dynamical models for these effects give rise to 10% corrections to the IAM. Alternatively the EPM can be used to relate the meson interaction effects that occur in β decay, muon capture and radiative pion capture.