COUPLED BARYON DIFFUSION AND NUCLEOSYNTHESIS IN THE EARLY UNIVERSE

We report on calculations of primordial nucleosynthesis in baryon-number inhomogeneous big bang models. Nucleosynthesis yields are presented as a function of Ωb for a range of parameters which characterize the amplitude, shape, and mean separation of isothermal baryon-number fluctuations assumed to arise from an earlier epoch. We follow the modification of these fluctuations due to neutron and proton diffusion before, during, and after nucleosynthesis, using a multizone computer code which couples the diffusion equation with the nuclear reaction network and the universal expansion. The resulting abundance yields are strongly dependent upon the parameters characterizing the fluctuations; however, there exists a range of these parameters in which the calculated light-element abundances are in agreement with observational constraints for considerably higher values of Ω6 than that allowed by the standard homogeneous big bang.