Calculated isospin-mixing corrections to Fermi β-decays in 1s0d-shell nuclei with emphasis on A = 34

Corrections to the Fermi matrix element due to analogue symmetry breaking are evaluated for the superallowed β-decays of ²²Mg, ³⁴Cl, and ³⁴Ar by considering the effects of Coulomb and other isospin-nonconserving potentials. Analogue symmetry breaking is calculated within the shell-model formalism by considering: (i) the deviations from unity of the radial overlap between the proton and neutron single-particle wave functions, and (ii) isospin mixing between states within the 0d$\text{5}\text{2}$0d$\text{3}\text{2}$0d$\text{1}\text{2}$ shell. The radial-overlap corrections for several cases of interest in the sd shell are evaluated with single-particle wave functions obtained from a self-consistent Hartree-Fock calculation. The sd-shell isospin-mixing corrections are calculated with an isospin-non-conserving potential which reproduces the experimental isobaric mass shifts. Comparisons with previous calculations are made. The Fermi matrix elements for the isospin-forbidden (β-decays of ³⁴Cl and ³⁴Ar to excited 0⁺ states are also calculated.