Primordial nucleosynthesis with massive τ neutrinos.
A massive long-lived τ neutrino in the MeV regime modifies the primordial light-element abundances predicted by big-bang nucleosynthesis (BBN) calculations. This effect has been used to derive limits on mnutau__. Because recently the observational situation has become somewhat confusing and, in part, intrinsically inconsistent, we reconsider the BBN limits on mnutau__. To this end we use our newly developed BBN code to calculate the primordial abundances as a function of mnutau__ and of the cosmic baryon density η. We derive concordance regions in the η-mnutau__-plane for several sets of alleged primordial abundances. In some cases a concordance region exists only for a nonvanishing mnutau__. At the present time BBN does not provide clear evidence for or against a τ neutrino mass.
Astronomy and Astrophysics
- Pub Date:
- November 1997
- ELEMENTARY PARTICLES;
- NUCLEAR REACTIONS;
- COSMOLOGY: EARLY UNIVERSE;
- High Energy Physics - Phenomenology
- 10 pages, latex-file, uses l-aa.sty and psfig.sty, 18 ps figures included