Particle physics catalysis of thermal 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. 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 8 orders of magnitude more efficient than the standard channel. In particle physics models where subsequent decay of X- does not lead to large nonthermal big bang nucleosynthesis 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 3x10(-17), which is one of the most stringent probes of electroweak scale remnants known to date.