PRIMORDIAL NUCLEOSYNTHESIS WITH MASSIVE TAU NEUTRINOS

A massive long-lived neutrino in the MeV regime modies the primordial light-element abundances predicted by big-bang nucleosynthesis (BBN) calculations. This effect has been used to derive limits on m. Because recently the ob- servational situation has become somewhat confusing and, in part, intrinsically inconsistent, we reconsider the BBN limits on m. To this end we use our newly developed BBN code to calculate the primordial abundances as a function of m and of the cosmic baryon density . We derive concordance regions in the -m-plane for several sets of alleged primordial abun- dances. In some cases a concordance region exists only for a nonvanishing m. At the present time BBN does not provide clear evidence for or against a neutrino mass.