Kosterlitz-Thouless universality in dimer models

Using the monomer-dimer representation of strongly coupled U(N) lattice gauge theories with staggered fermions, we study finite temperature chiral phase transitions in 2+1 dimensions. A new cluster algorithm allows us to compute monomer-monomer and dimer-dimer correlations at zero monomer density (chiral limit) accurately on large lattices. This makes it possible to show convincingly, for the first time, that these models undergo a finite temperature phase transition which belongs to the Kosterlitz-Thouless universality class. We find that the phase transition persists for all values of N, but occurs at different values of the critical temperature T-c. Further, when T/T-c is held fixed, the mean field analysis often used in the large N limit breaks down.