Critical behavior of mean-field XY and related models

We discuss spin models on complete graphs in the mean-field (infinite-vertex) limit, especially the classical XY model, the Toy model of the Higgs sector, and related generalizations. We present a number of results coming from the theory of large deviations and Stein's method, in particular, Cram\'er and Sanov-type results, limit theorems with rates of convergence, and phase transition behavior for these models.