A nontrivial Renormalization Group fixed point for the Dyson-Baker hierarchical model

We prove the existence of a nontrivial Renormalization Group (RG) fixed point for the Dyson-Baker hierarchical model ind=3 dimensions. The single spin distribution of the fixed point is shown to be entire analytic, and bounded by exp(–const×t ⁶) for large real values of the spint. Our proof is based on estimates for the zeros of a RG fixed point for Gallavotti's hierarchical model. We also present some general results for the heat flow on a space of entire functions, including an order preserving property for zeros, which is used in the RG analysis.Supported in Part by the National Science Foundation under Grant No. DMS-9103590.Supported in Part by the Swiss National Science Foundation.