  It has been proposed that the apparent discrepancies between the inferred
primordial abundances of 6Li and 7Li and the predictions of big bang
nucleosynthesis (BBN) can be resolved by the existence of a negatively-charged
massive unstable supersymmetric particle (X-) during the BBN epoch. Here, we
present new BBN calculations with an X- particle utilizing an improved nuclear
reaction network including captures of nuclei by the particle, nuclear
reactions and beta-decays of normal nuclei and nuclei bound to the X- particles
(X-nuclei), and new reaction rates derived from recent rigorous quantum
many-body dynamical calculations. We find that this is still a viable model to
explain the observed 6Li and 7Li abundances. However, contrary to previous
results, neutral X-nuclei cannot significantly affect the BBN light-element
abundances. We also show that with the new rates the production of heavier
nuclei is suppressed and there is no signature on abundances of nuclei heavier
than Be in the X--particle catalyzed BBN model as has been previously proposed.
We also consider the version of this model whereby the X- particle decays into
the present cold dark matter. We analyze the this paradigm in light of the
recent constraints on the dark-matter mass deduced from the possible detected
events in the CDMS-II experiment. We conclude that based upon the inferred
range for the dark-matter mass, only X- decay via the weak interaction can
achieve the desired 7Li destruction while also reproducing the observed 6Li
abundance.
