Properties of Active-Neutrino Oscillations and Double-Beta Decay in the Presence of Sterile-Neutrino Contributions

The contributions of light sterile neutrinos to the properties of active-neutrino oscillations and the properties of double-beta decay are estimated under the assumption of the Majorana nature of neutrinos on the basis of a phenomenological model involving three active and three sterile neutrinos. The appearance and survival probabilities for active neutrinos are determined upon taking into account sterile-neutrino contributions in order to explain all known anomalies in neutrino data at short distances by employing the same test values of the model parameters. Modified graphical dependences of the survival and appearance probabilities for electron neutrinos/antineutrinos in beams of muon neutrinos/antineutrinos on the distance and other model parameters at various neutrino energies, as well as on the ratio of the distance to the neutrino energy, are presented. A significant distinction between the probability curves within the neutrino model being considered and the simple sinusoidal curves based on the neutrino model involving only one sterile neutrino is found. The effective electron-neutrino masses for beta decay and for neutrinoless double-beta decay are estimated in the presence of the sterile-neutrino contributions. In addition, the properties of selenium-82 two-neutrino double-beta decay are calculated. These results can be used in interpreting and predicting the results of ground-based experiments aimed at searches for sterile neutrinos and neutrinoless double-beta decay.