Catalyzed Big-Bang nucleosynthesis

We point out that the existence of metastable, tau > 10(3) s, negatively charged electroweak-scale particles (X-) alters the predictions for lithium and other primordial elemental abundances for A > 4 via the formation of bound states with nuclei during Big-Bang nucleosynthesis (BBN). In particular, we show that the bound states of X- with helium, formed at temperatures of about T = 10(8) K, lead to the catalytic enhancement of Li-6 production, which is eight orders of magnitude more efficient than the standard channel. In particle physics models, where subsequent decay of X- does not lead to large nonthermal BBN effects, this directly translates to the level of sensitivity to the number density of long-lived X- particles (tau > 10(5) s) relative to entropy of n(X)-/s less than or similar to 3 x 10(-17), which is one of the most stringent probes of electroweak scale remnants known to date. It is also argued that unstable charged particles with lifetime of order similar to 2000 s. may naturally lead to the depletion of Li-7 by a factor of two, making it consistent with observationally determined abundances.