Big-bang nucleosynthesis in a Brans-Dicke cosmology with a varying

We investigate the big-bang nucleosynthesis in a Brans-Dicke model with a varying Λ term using the Monte-Carlo method and likelihood analysis. It is found that the cosmic expansion rate differs appreciably from that of the standard model. The produced abundances of 4He, D, and 7Li are consistent with the observed ones within the uncertainties in nuclear reaction rates when the baryon to photon ratio $\eta = \left( 5.47{-}6.64 \right)$ $\times$ $10^{-10}_{}$, which is in agreement with the value deduced from WMAP