Primordial nucleosynthesis: The effects of injecting hadrons

We place constraints on the abundance of quasistable particles with hadronic decay modes using the upper bounds on primordially produced ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ and the sum of D and ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ abundances. The results are presented as a function of particle lifetime (ranging between ${10}^{\mathrm{-}1}$ and ${10}^4$ sec), particle mass, and hadronic branching ratio. We apply our results to the cases of gravitinos, photinos in R̃-parity-violating theories, and mirror quarks. We also discuss another mechanism for hadron injection: cold-dark-matter annihilation.