Regular Article - Experimental Physics
Superallowed decays within and beyond the standard model
IJC-Lab, Université Paris-Saclay, CNRS/IN2P3, 15 rue G. Clémenceau, 91405, Orsay, France
2 Department de Física Teòrica IFIC, Universitat de València-CSIC, Parc Científic, 46980, Paterna, Valencia, Spain
3 Facility for Rare Isotope Beams and Department of Physics and Astronomy, Michigan State University, 640 S Shaw Lane, 48824, East Lansing, MI, USA
4 LPC-Caen, CNRS/IN2P3, Université de Caen Normandie, 6 bd Maréchal Juin, 14000, Caen, France
5 Instituut voor Kern-en Stralingsfysika, KU Leuven, Celestijnenlaan 200D, 3001, Leuven, Belgium
Accepted: 8 May 2023
Published online: 24 May 2023
This note reviews the role of superallowed transitions in determining the strength of the weak interaction among the lightest quarks and in searching for new physics beyond the standard electroweak model. The two sets of superallowed decays in nuclei considered here are pure Fermi and mirror transitions. The first have been scrutinized for more than 50 years. The most relevant results are presented and the role of the nucleus-dependent radiative correction and nucleus-independent inner radiative correction are reviewed. In this context, the systematic study of mirror transitions started about 15 years ago. Despite the significant progress made since then, the data is still limited by experimental uncertainties. Combining the results from all superallowed transitions, which are fully consistent, provides a test of unitarity of the first row of the Cabibbo-Kobayashi-Maskawa matrix, which displays a 2 tension with the standard model.
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