Hadronic decay of late-decaying particles and big-bang nucleosynthesis

We study the big-bang nucleosynthesis (BBN) scenario with late-decaying exotic particles with lifetime longer than similar to 1 s. With a late-decaying particle in the early universe, predictions of the standard BBN scenario can be significantly altered. Therefore, we derive constraints on its primordial abundance. We pay particular attention to hadronic decay modes of such particles. We see that the non-thermal production process of D, He-3 and Li-6 provides a stringent upper bound on the primordial abundance of late-decaying particles with hadronic branching ratio. (c) 2005 Elsevier B.V. All rights reserved.