Big Bang Nucleosynthesis with Bound States of Long-lived Charged   Particles
  Charged particles (X) decaying after primordial nucleosynthesis are constrained by the requirement that their decay products should not change the light element abundances drastically. If the decaying particle is negatively charged (X-) then it will bind to the nuclei. We consider the effects of the decay of X when bound to Helium-4 and show that this will modify the Lithium abundances. 
Manoj Kaplinghat and Arvind Rajaraman