Measurements on superallowed 0⁺ \rightarrow 0⁺ nuclear beta transitions currently provide the most demanding test of the Conserved Vector Current (CVC) hypothesis and the most precise value for the up-down element, V_ud, of the Cabibbo–Kobayashi–Maskawa (CKM) matrix. Both are sensitive probes for physics beyond the Standard Model. Analysis of the experimental results depends on small radiative and isospin-symmetry-breaking corrections, some of which depend on the specific structure of the parent and daughter nuclei involved. These calculated corrections affect the precision of the results, and experiments are currently focused on reducing their uncertainties. Although nuclear structure only contributes to rather small corrections, it plays a crucial role in these fundamental tests.

PACS numbers: 23.40.Bw, 12.15.Hh