Field theory for charged fluids and colloids

Charged systems are considered using field theoretic methods which include fluctuations and correlations via a systematic expansion in powers of the l ocal electrostatic potential. At the Gaussian level we recover the classica l Debye-Huckel (DH) theory, which is found to exhibit the full hierarchy of multibody correlations determined by pair-distribution functions given ty the screened DH potential. Higher-order corrections can lead to attractive pair interactions between similarly charged particles in asymmetric ionic e nvironments. The phase diagram for an ionic fluid shows a critical paint of demixing. The critical temperature and critical density exhibit pronounced deviations from DH theory for highly asymmetric ionic systems.