Confinement and chiral condensates in 2d QED with massive N-flavor fermions

We evaluate Polyakov loops and string tension in two-dimensional QED with both massless and massive N-flavor fermions at zero and finite temperature. External charges, or external electric fields, induce phases in fermion masses and shift the value of the vacuum angle parameter θ, which in turn alters the chiral condensate. In particular, in the presence of two sources of opposite charges, q and −q, the shift in θ is 2π(qe) independent of N. The string tension has a cusp singularity at θ = ±π for N ≥ 2 and is proportional to m2N(N+1) at T = 0.