Sterile Neutrinos and Big Bang Nucleosynthesis

We calculate primordial element abundances in the presence of neutrino spectral distortion resulting from active-sterile transformation. We find that the effects of adding a significant lepton number to the big bang nucleosynthesis calculation are reversed when we include nonthermal distorted spectra. Our results show that this can be true for a variety of $\nu_e$ and $\bar\nu_e$ spectral distortions arising from various active-sterile transformation processes.