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Superallowed Beta Decay of Nuclei with A >or= 62: The Limiting Effect of Weak Gamow-Teller Branches

J. C. Hardy·I. S. Towner
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Abstract

The most precise value of V_{ud}, which is obtained from superallowed nuclear beta decay, leads to a violation of CKM unitarity by 2.2 sigma. Experiments are underway on two continents to test and improve this result through decay studies of odd-odd N = Z nuclei with A >or= 62. We show, in a series of illustrative shell-model calculations, that numerous weak Gamow-Teller branches are expected to compete with the superallowed branch in each of these nuclei. Though the total Gamow-Teller strength is significant, many of the individual branches will be unobservably weak. Thus, new techniques must be developed if reliable ft-values are to be obtained with 0.1% precision for the superallowed branches.

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J. C. Hardy, I. S. Towner. 2003-08-01. Superallowed Beta Decay of Nuclei with A >or= 62: The Limiting Effect of Weak Gamow-Teller Branches. https://doi.org/10.1103/physrevlett.88.252501

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