Neutrino quantum beats

Abstract

The strong and convincing evidence in favor of non-vanishing neutrino masses and oscillations has ignited a vivid discussion of the physical implications of neutrino flavor mixing and the standard model in general. According to recent experimental data at GSI, the number of daughter nuclei 140Ce58 per time interval, produced by the nuclear K-shell electron capture (EC) decay of the hydrogen-like ion 140Pr58+, is modulated in time. This phenomenon can be explained by neutrino-flavor mixing. Assuming, for simplicity, two-neutrino-flavor mixing the decay rate and the rate of daughter nuclei 140Ce58+ as a function of time is calculated. The results explain well the preliminary experimental data by GSI and can be easily extended to three-neutrino-flavor mixing and so on. The fundamental theoretical concepts of bound beta decay and its timereversed process, K-electron capture decay, as well as of neutrino flavor mixing are discussed. In addition, the first experimental observations of weak two-body decays such as the 163Dy, 187Re and 207Tl experiments at GSI Darmstadt are presented.