Finite temperature effects on cosmological baryon diffusion and inhomogeneous big-bang nucleosynthesis

We have studied finite temperature corrections to the baryon transport cross sections and diffusion coefficients. These corrections are based upon our recently computed renormalized electron mass and modified state density due to the background thermal bath in the early universe. It is found that the optimum nucleosynthesis yields computed using our diffusion coefficients shift to longer distance scales by a factor of about 3. We also find that the primordial ${}^4\mathrm{He}$ abundance decreases by $\Delta Y_p\simeq 0.01$ while D and ${}^7\mathrm{Li}$ increase. The effects of these results on constraints from primordial nucleosynthesis are discussed. In particular, we find that a large baryonic contribution to the closure density $({\Omega }_b{h}_{50}^2\lesssim 0.4)$ may be allowed in inhomogeneous models corrected for finite temperature.