Big-bang nucleosynthesis in Brans-Dicke cosmology with a varying $\hat{I}›$ term related to WMAP

Abstract

We investigate the big-bang nucleosynthesis in a Brans-Dicke model with a varying $\hat{I}›$ 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 ${}^4$He, D, and barely Li are consistent with the observed ones within the uncertainties in nuclear reaction rates when the baryon to photon ratio $\hat{I}\cdot =(5.47-6.64)\times 10^{-10}$, which is in agreement with the value deduced from WMAP.

Submitted to A&A, 5 pages, 7 figures