Dimer geometry, amoebae and a vortex dimer model

TL;DR

This paper introduces a geometric framework for dimer models on graphs, exploring connections with non-trivial holonomy and curvature, and studies the phase diagram via amoebae, including models with vortices and negative edge weights.

Contribution

It develops a novel geometric approach to dimer problems, incorporating connections with holonomy and curvature, and analyzes vortex effects through amoebae structures.

Findings

Holonomy in bipartite graphs is universal and unaffected by graph size.

Non-bipartite models exhibit non-zero curvature and Chern number without magnetic fields.

Vortices lead to new amoeba structures and relate to massless Dirac doublets.

Abstract

We present a geometrical approach for studying dimers. We introduce a connection for dimer problems on bipartite and non-bipartite graphs. In the bipartite case the connection is flat but has non-trivial ${\bf Z}_2$ holonomy round certain curves. This holonomy has the universality property that it does not change as the number of vertices in the fundamental domain of the graph is increased. It is argued that the K-theory of the torus, with or without punctures, is the appropriate underlying invariant. In the non-bipartite case the connection has non-zero curvature as well as non-zero Chern number. The curvature does not require the introduction of a magnetic field. The phase diagram of these models is captured by what is known as an amoeba. We introduce a dimer model with negative edge weights that give rise to vortices. The amoebae for various models are studied with particular emphasis on the case of negative edge weights which corresponds to the presence of vortices. Vortices gives rise to new kinds of amoebae with certain singular structures which we investigate. On the amoeba of the vortex full hexagonal lattice we find the partition function corresponds to that of a massless Dirac doublet.