Model-Independent Determination of Nuclear Weak Form Factors and Implications for Standard Model Precision Tests.

Abstract

We analyze the recoil corrections in superallowed beta decays of T=1, J^{P}=0^{+} nuclei by fixing the mean square charged weak radius model independently using the data of multiple charge radii across the nuclear isotriplet. By comparing to model estimations, we argue that the existing theory uncertainty in the statistical rate function f might have been substantially underestimated. We discuss the implications of our proposed strategy for precision tests of the standard model, including a potential alleviation of the first-row CKM unitarity deficit, and motivate new experiments for charge radii measurements.