Thin Fisher zeros

Various authors have suggested that the loci of partition function zeros ca n profitably be regarded as phase boundaries in the complex temperature or field planes, We obtain the Fisher zeros for Ising and Potts models on non- planar ('thin') regular random graphs using this approach, and note that th e locus of Fisher zeros on a Bethe lattice is identical to the correspondin g random graph. Since the number of states q appears as a parameter in the Potts solution the limiting locus of chromatic zeros is also accessible.