The ${}^6\mathrm{Li}$ abundance observed in metal-poor halo stars exhibits a plateau similar to that for ${}^7\mathrm{Li}$ suggesting a primordial origin. However, the observed abundance of ${}^6\mathrm{Li}$ is a factor of ${10}^3$ larger and that of ${}^7\mathrm{Li}$ is a factor of 3 lower than the abundances predicted in the standard big bang when the baryon-to-photon ratio is fixed by Wilkinson microwave anisotropy probe. Here we show that both of these abundance anomalies can be explained by the existence of a long-lived massive, negatively charged leptonic particle during nucleosynthesis. Such particles would capture onto the synthesized nuclei thereby reducing the reaction Coulomb barriers and opening new transfer reaction possibilities, and catalyzing a second round of big bang nucleosynthesis. This novel solution to both of the Li problems can be achieved with or without the additional effects of stellar destruction.

• Received 22 June 2007

DOI:https://doi.org/10.1103/PhysRevD.76.121302