Refined shell-model matrix elements for muon-capture processes

Recently many shell-model calculations have been performed in order to extr act the value of the ratio C-P/C-A in light nuclei. Most of these calculati ons fail to reproduce the value given by the partially conserved axial vect or hypothesis, roughly 7. We show, that by using the effective transition o perators, calculated by the perturbative techniques, this discrepancy can b e, at least partly, solved. New angular correlation data for Si-28 is used for the extraction of C-P/C-A In the case of Ne-20, the capture rate data i s used for extraction.