Data-driven reevaluation of ft values in superallowed β decays

Efforts toward a precise determination of V_u00exd and low-energy tests of the electroweak Standard Model have been ongoing for many years. The authors report a comprehensive re-evaluation of the f00ext values in superallowed nuclear β decays based on a fully data-driven analysis of the nuclear β-decay form factor. They utilize isospin relations to connect the nuclear charged weak distribution to the measurable charge distributions. The approach supersedes previous shell-model estimations and allows for a rigorous quantification of theory uncertainties in the phase-space factor, using experimental input rather than nuclear models. The work identifies the need for specific future experimental research to drive further understanding toward a regime of precision that is relevant for weak-interaction physics and thus for physics beyond the Standard Model.