Neutron beta-decay and the unitarity condition of the CKM matrix

An important aspect of the universality of the electroweak interaction in t he Standard Model is the unitarity condition of the Cabibbo-Kobayashi-Maska wa (CKM) matrix. By comparing neutron decay data, based upon quark decays o f the first particle family, with the results of quark decays of the second and third particle families, we can rest the unitarity condition of the CK M matrix. The result differs by more than 2 sigma standard deviation from t he unitarity condition. This check is based solely on particle decay data.