How unitarity in the CKM matrix of quark interactions was proven correct

Abstract

In 1993, a new Hyperon Beta Decay study was introduced into the KTeV experiment and although it would have only collected less than 1000 events, it was to become a major important step in particle physics, because it showed that the CKM matrix obeyed unitarity. This new idea was introduced by myself while a new PostDoc just starting my career after getting a Ph.D. The 98% analyzing power of these decays allowed us to study beta decay form factors and showed that the CKM matrix element Vus historically used for 35 years was wrong and that this correction changed Vus by 6 sigma bringing a new understanding to quark flavor physics. Today the CKM matrix is a guide for a similar matrix in the neutrino matrix and continues to have an important impact on particle quark flavor searches for new physics.