Active and Sterile Neutrino Mass Effects on Beta Decay Spectra

We study the spectra of the emitted charged leptons in charge current weak nuclear processes to analyze the effect of neutrino masses. Standard active neutrinos are studied here, with masses of the order of 1 eV or lower, as well as sterile neutrinos with masses of a few keV. The latter are warm dark matter (WDM) candidates hypothetically produced or captured as small mixtures with the active neutrinos. We compute differential decay or capture rates spectra in weak charged processes of different nuclei (H-3, Re-187, Pd-107, Ho-163, etc) using different masses of both active and sterile neutrinos and different values of the mixing parameter.