For many decades, the main source of information on the top-left corner element of the Cabibbo–Kobayashi–Maskawa quark mixing matrix, V ud , was superallowed nuclear β decays with an impressive 0.01% precision. This precision, apart from experimental data, relies on theoretical calculations in which nuclear structure–dependent effects and uncertainties play a prime role. This review is dedicated to a thorough reassessment of all ingredients that enter the extraction of the value of V ud from experimental data. We try to keep balance between historical retrospect and new developments, many of which occurred in just the past 5 years. They have not yet been reviewed in a complete manner, not least because new results are forthcoming. This review aims to fill this gap and offers an in-depth yet accessible summary of all recent developments.

中文翻译：

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标准模型的超允许核 β 衰变和精度检验


几十年来，关于 Cabibbo-Kobayashi-Maskawa 夸克混合矩阵左上角元素 V ud 的主要信息来源是超允许的核β衰变，精度高达 0.01%。除了实验数据外，这种精度还依赖于理论计算，其中核结构依赖性效应和不确定性起着主要作用。本综述致力于对从实验数据中提取 V ud 值的所有成分进行彻底的重新评估。我们试图在历史回顾和新发展之间保持平衡，其中许多发展仅发生在过去 5 年中。它们尚未经过全面审查，尤其是因为新的结果即将出炉。这篇评论旨在填补这一空白，并对所有最近的发展进行了深入而易懂的总结。