Inhomogeneous big-bang nucleosynthesis in light of recent observations

We consider inhomogeneous big-bang nucleosynthesis in light of the present observational situation. We give updated limits to the baryon-to-photon ratio and ${\Omega }_b$ and show that the inhomogeneous nucleosynthesis may alleviate the tension between ${}^4\mathrm{He}$ and D observations. The recent Kamiokande results are shown to strongly disfavor the decaying $\tau$ neutrino solution to this tension. The possible sources of baryon inhomogeneity include the QCD and electroweak phase transitions (EWPT). It is found that EWPT produces a distinct “beer foam” geometry of inhomogeneity, but that the distance scale is too small for them to have a large effect on nucleosynthesis; the effect may still be larger than some of the other small corrections recently incorporated to SBBN codes.