Anomalous neutrino interactions and primordial nucleosynthesis

This paper examines the effect on primordial nucleosynthesis of anomalous interactions which allow neutrinos to remain in thermal contact with other matter through the period of pair annihilation in the early Universe. Such interactions are a possible consequence of the non-vanishing mass for at least one neutrino suggested by the experiment of Reines et al. In addition, the effect of a light tau neutrino is examined by way of comparison. The production of deuterium, which of the light elements proves most sensitive to these alterations, is found in the former case to increase by roughly a factor of 2 in the regime of cosmological interest, while helium shows minor changes. (author)