Calculated values of the nuclear-mismatch correction for superallowed 0+→0+ beta decays

Numerical calculations of the nuclear-mismatch correction δ C for superallowed 0 + →0 + beta decays are made from formulae previously developed using the formalism of R-matrix theory. The present values of δ C are considerably smaller than those obtained in previous calculations, and lead to ft -values that are not consistent with either the CVC hypothesis or unitarity of the KM mixing matrix.