Radiative Corrections to Superallowed β Decays in Effective Field Theory

Area of Science:

• Nuclear Physics
• Particle Physics
• Quantum Field Theory

Background:

• Accurate determination of V_{ud} is crucial for the Standard Model.
• Superallowed β decays are a primary source for V_{ud} values.
• Radiative corrections, particularly nucleus-dependent ones (δ_{NS}), limit V_{ud} precision.

Purpose of the Study:

• To develop a theoretical framework for calculating nucleus-dependent radiative corrections (δ_{NS}).
• To utilize effective field theory (EFT) to constrain δ_{NS} and improve V_{ud} accuracy.
• To compare EFT predictions with dispersive representations of δ_{NS}.

Main Methods:

• Application of effective field theory (EFT) to calculate δ_{NS}.
• Identification of dominant terms in the EFT expansion.
• Comparison of EFT results with dispersive calculations of δ_{NS}.

Main Results:

• The EFT power counting successfully predicts the dominant contributions to δ_{NS}.
• The momentum scaling of δ_{NS} is observed to hold even for low-lying intermediate states.
• A clear path towards ab initio calculations of δ_{NS} is established.

Conclusions:

• The proposed EFT framework offers a rigorous method to calculate δ_{NS}.
• This approach directly tackles the main uncertainty in V_{ud} determinations.
• The study advances the precision of fundamental parameters in the Standard Model.