NEUTRINO HEAT-CONDUCTION AND INHOMOGENEITIES IN THE EARLY UNIVERSE

Constraints on parameters of inhomogeneous nucleosynthesis, namely, th e overdensity and size of baryon lumps are found by calculating the bl ackbody neutrino heat conduction into the lumps, which tends to inflat e them away. The scale size for efficient heat conduction is determine d by the mean free path lambda of the neutrino, and so we compute lamb da in our case of a high-temperature plasma with low chemical potentia l, and find a general result that many-body effects are unimportant, s implifying the calculation. We find that in the region of interest for nucleosynthesis, neutrino inflation is important for overdensities > 10(4).