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 ${}^7\mathrm{Li}$ 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 $(100–120)\mathrm{MeV}$. We can therefore simultaneously explain the abundance of the dark matter and that of ${}^7\mathrm{Li}$ by these values of parameters. The lifetime of staus in this scenario is predicted to be $O(100–1000)\sec$.

• Received 27 May 2008

DOI:https://doi.org/10.1103/PhysRevD.78.055007