Big-bang nucleosynthesis and the relic abundance of dark matter in a stau-neutralino coannihilation scenario

A scenario of the big-bang nucleosynthesis is analyzed within the minimal supersymmetric standard model, which is consistent with a stau-neutralino coannihilation scenario to explain the relic abundance of dark matter. We find that we can account for the possible discrepancy of the abundance of Li-7 between the observation and the prediction of the big-bang nucleosynthesis by taking the mass of the neutralino as 300 GeV and the mass difference between the stau and the neutralino as (100-120) MeV. We can therefore simultaneously explain the abundance of the dark matter and that of Li-7 by these values of parameters. The lifetime of staus in this scenario is predicted to be O(100-1000) sec