Bounds on long-lived charged massive particles from Big Bang nucleosynthesis

The Big Bang nucleosynthesis (BBN) process in the presence of charged massive particles (CHAMPs) is studied in detail. All currently known effects due to the existence of bound states between CHAMPs and nuclei, including possible late-time destruction of Li-6 and Li-7, are included. The study sets conservative bounds on CHAMP abundances in the decay time range 3 x 10(2) s less than or similar to T-x less than or similar to 10(12) s. It is stressed that the production of 6Li at early times T similar to 10 keV is overestimated by a factor similar to 10 when the approximation of the Saha equation for the He-4 bound state fraction is utilized. To obtain conservative limits on the abundance of CHAMPs, a Monte Carlo analysis with similar to 3 x 10(6) independent BBN runs, varying the reaction rates of 19 different reactions, is performed. The analysis yields the surprising result that, except for small areas in the particle parameter space, conservative constraints on the abundance of decaying charged particles are currently very close to those of neutral particles. It is shown that, in the case that the rates of a number of heretofore unconsidered reactions may be determined reliably in the future, it is conceivable that the limit on CHAMPs in the early Universe could be tightened by orders of magnitude.