In this paper we consider the effects on big bang nucleosynthesis (BBN) of the hadronic decay of a long-lived massive particle. If high-energy hadrons are emitted near the BBN epoch $(t\sim {10}^{-2}–{10}^2\sec ),$ they extraordinarily interconvert the background nucleons with each other even after the freeze-out time of the neutron to proton ratio. Then, the produced light element abundances are changed, and that may result in a significant discrepancy between standard BBN and observations. Especially on the theoretical side, we can now obtain a lot of experimental data on hadrons and simulate the hadronic decay process, executing the numerical code of the hadron fragmentation even in the high energy region where we have no experimental data. Using the computed light element abundances in the hadron-injection scenario, we derive a constraint on the properties of such a particle by comparing our theoretical results with observations.

• Received 31 March 2001

DOI:https://doi.org/10.1103/PhysRevD.64.043515