Big Bang nucleosynthesis with long-lived strongly interacting relic particles

We study effects of relic long-lived strongly interacting massive particles (X particles) on big bang nucleosynthesis (BBN). The X particle is assumed to have existed during the BBN epoch, but decayed long before detected. The interaction strength between an X and a nucleon is assumed to be similar to that between nucleons. Rates of nuclear reactions and beta decay of X-nuclei are calculated, and the BBN in the presence of neutral charged X⁰ particles is calculated taking account of captures of X⁰ by nuclei. As a result, the X⁰ particles form bound states with normal nuclei during a relatively early epoch of BBN leading to the production of heavy elements. Constraints on the abundance of X⁰ are derived from observations of primordial light element abundances. Particle models which predict long-lived colored particles with lifetimes longer than ~200 s are rejected. This scenario prefers the production of ⁹Be and ¹⁰B. There might, therefore, remain a signature of the X particle on primordial abundances of those elements. Possible signatures left on light element abundances expected in four different models are summarized.