DIFFUSION AND DEBYE-SCREENING NEAR EXPANDING DOMAIN-WALLS

We study the effect of Debye screening of hypercharge when a net fermi on number is reflected from a domain wall during a first order phase t ransition, which may be relevant for electroweak baryogenesis. We give a simple method for computing the effect of screening within the diff usion approximation, whose results are compatible with those of a more elaborate treatment based on the Boltzmann equation. Our formalism ta kes into account the differences in mobility of different particle spe cies, We believe it is conceptually simpler than other accounts of scr eening that have appeared in this context, Somewhat surprisingly, we f ind that Debye screening can actually enhance electroweak baryogenesis by a modest factor (similar to 2).