Criticality and conformality in the random dimer model

In critical systems, the effect of a localized perturbation affects points that are arbitrarily far from the perturbation location. In this paper, we study the effect of localized perturbations on the solution of the random dimer problem in two dimensions. By means of an accurate numerical analysis, we show that a local perturbation of the optimal covering induces an excitation whose size is extensive with finite probability. We compute the fractal dimension of the excitations and scaling exponents. In particular, excitations in random dimer problems on nonbipartite lattices have the same statistical properties of domain walls in spin glass. Excitations produced in bipartite lattices, instead, are compatible with a loop-erased self-avoiding random walk process. In both cases, we find evidence of conformal invariance of the excitations that is compatible with SLE kappa with parameter kappa depending on the bipartiteness of the underlying lattice only.

Automated summary

This paper investigates the effect of localized perturbations on the solution of the random dimer problem in two dimensions, finding that a local perturbation of the optimal covering induces an extensive excitation with finite probability. The statistical properties of excitations in random dimer problems differ on bipartite and nonbipartite lattices, with evidence of conformal invariance compatible with SLE kappa, depending on the bipartiteness of the lattice.