Anomalous Behavior in the Massive Schwinger Model

Abstract

We evaluate the chiral condensate and Polyakov loop in two-dimensional QED with a fermion of an arbitrary mass ($m$). We find discontinuous $m$ dependence in the chiral condensate and anomalous temperature dependence in Polyakov loops when the vacuum angle $\theta$$\sim$$\pi$ and $m$=O($e$). These nonperturbative phenomena are due to the bifurcation process in the solutions to the vacuum eigenvalue equation.