Nuclear reaction rates and primordial<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow/><mml:mrow><mml:mn>6</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>Li

We examine the possibility that big-bang nucleosynthesis (BBN) may produce nontrivial amounts of ${}^{6}\mathrm{Li}$. 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 ${}^{6}\mathrm{Li}$ abundance are extremely uncertain due to difficulties in both theoretical estimates and experimental determinations of the ${}^{2}\mathrm{H}(\ensuremath{\alpha},\ensuremath{\gamma}{)}^{6}\mathrm{Li}$ radiative capture reaction cross section. We also argue that present observational capabilities do not yet allow the detection of primeval ${}^{6}$Li 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 ${}^{6}\mathrm{Li}$ detection capabilities may allow the establishment of ${}^{6}\mathrm{Li}$ as another product of BBN. It is also noted that a primordial ${}^{6}\mathrm{Li}$ detection could help resolve current concerns about the extragalactic D/H determination.

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