Tensor network formulation of the massless Schwinger model

Abstract: We construct a tensor network representation of the partition function for the massless Schwinger model on a two dimensional lattice using staggered fermions. The tensor network representation allows us to include a topological term. Using a particular implementation of the tensor renormalization group (HOTRG) we calculate the phase diagram of the theory. For a range of values of the coupling to the topological term $\theta$ and the gauge coupling $\beta$ we compare with results from hybrid Monte Carlo when possible and find good agreement.