Glassiness and constrained dynamics of a short-range nondisordered spin model

We study the low temperature dynamics of a two-dimensional short-range spin system with uniform ferromagnetic interactions, which displays glassiness at low temperatures despite the absence of disorder or frustration. The model has a dual description in terms of free defects subject to dynamical constraints, and is an explicit realization of the "hierarchically constrained dynamics" scenario for glassy systems. We give a number of exact results for the statics of the model, and study in detail the dynamical behavior of one-time and two-time quantities. We also consider the role played by the configurational entropy, which can be computed exactly, in the relation between fluctuations and response.