A general Lee-Yang theorem for one-component and multicomponent ferromagnets

We show that any measure on Rsup(n) possessing the Lee-Yang property retains that property when multiplied by a ferromagnetic pair interaction. Newman's Lee-Yang theorem for one- component ferromagnets with general single-spin measure is an immediate consequence. We also prove an analogous result for two-component ferromagnets. For N-component ferromagnets (N >= 3), we prove a Lee-Yang theorem when the interaction is sufficiently anisotropic. (orig.)