SU(4) breaking, allowed transitions and total muon capture rates in nuclei

The authors study muon capture rates in light nuclei and show that one can evaluate them in a model-independent way by correcting the Primakoff closure approximation to the first order in the neutrino energy dependence. In this framework the interplay between the existence of allowed transitions and SU(4) breaking is analyzed. In the correction to the first order in the neutrino energy dependence by a sum rule, Majorana and SU(4) breaking potentials are taken into account. The method is also applied to single multipolar transitions, in particular for the dipole transitions. General considerations are illustrated for /sup 6/Li and /sup 12/C by explicit calculations. The stability of the results varying the mean neutrino energy allows the use of capture rates as a very sensitive tool to investigate the configuration mixing of the target because we connect the corrective term to spectroscopic information using directly the matrix elements of the effective potentials. (10 refs).