Data-driven reevaluation of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>f</mml:mi><mml:mi>t</mml:mi></mml:mrow></mml:math> values in superallowed <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>β</mml:mi></mml:math> decays
Chien-Yeah Seng, Mikhail Gorchtein
Abstract
Efforts toward a precise determination of ${V}_{u\phantom{\rule{0}{0ex}}d}$ and low-energy tests of the electroweak Standard Model have been ongoing for many years. The authors report a comprehensive re-evaluation of the $f\phantom{\rule{0}{0ex}}t$ values in superallowed nuclear $\ensuremath{\beta}$ decays based on a fully data-driven analysis of the nuclear $\ensuremath{\beta}$-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.