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

Area of Science:

• Nuclear physics
• Particle physics
• Quantum chromodynamics

Background:

• Superallowed beta decays provide sensitive probes of the weak interaction.
• Precise measurements are crucial for testing the Standard Model (SM) and searching for new physics.
• Nuclear structure effects, like recoil corrections, introduce theoretical uncertainties.

Purpose of the Study:

• To refine the analysis of recoil corrections in T=1, J^P=0+ superallowed beta decays.
• To independently constrain the mean square charged weak radius model.
• To reassess theoretical uncertainties in the statistical rate function f.

Main Methods:

• Utilizing data from multiple charge radii measurements across nuclear isospin triplets.
• Applying a constrained mean square charged weak radius model.
• Comparing model estimations with experimental data.

Main Results:

• The study indicates a substantial underestimation of existing theory uncertainties in the statistical rate function f.
• A new strategy for analyzing recoil corrections is proposed.
• The findings have implications for precision tests of the Standard Model.

Conclusions:

• The proposed method offers a more robust approach to analyzing superallowed beta decays.
• Underestimated theoretical uncertainties may affect the interpretation of the first-row CKM unitarity.
• New experiments measuring nuclear charge radii are motivated to improve precision.