Nuclear reaction rates and primordial ⁶Li

We examine the possibility that big-bang nucleosynthesis (BBN) may produce nontrivial amounts of ⁶Li. If a primordial component of this isotope could be observed, it would provide a new fundamental test of big-bang cosmology, as well as new constraints on the baryon density of the universe. At present, however, theoretical predictions of the primordial ⁶Li abundance are extremely uncertain due to difficulties in both theoretical estimates and experimental determinations of the ²H(α,γ)⁶Li radiative capture reaction cross section. We also argue that present observational capabilities do not yet allow the detection of primeval ⁶Li in very metal-poor stars of the galactic halo. However, if the critical cross section is very high in its plausible range and the baryon density is relatively low, then improvements in ⁶Li detection capabilities may allow the establishment of ⁶Li as another product of BBN. It is also noted that a primordial ⁶Li detection could help resolve current concerns about the extragalactic D/H determination.