Universality of the mean-field for the Potts model

Weconsider the Pottsmodelwith q colors on a sequence ofweighted graphs with adjacency matrices An , allowing for both positive and negative weights. Under a mild regularity condition on An we show that the mean-field prediction for the log partition function is asymptotically correct, whenever tr(An) = o(n). In particular, our results are applicable for the Ising and the Potts models on any sequence of graphs with average degree going to +∞. Using this, we establish the universality of the limiting log partition function of the ferromagnetic Potts model for a sequence of asymptotically regular graphs, and that of the Ising model for bi-regular bipartite graphs in both ferromagnetic and anti-ferromagnetic domain. We also derive a large deviation principle for the empirical measure of the colors for the Potts model on asymptotically regular graphs.