Invariant fermion correlator in the Schwinger model on the torus.

We construct the gauge invariant fermion correlator in the Schwinger model on the torus. At zero temperature, this correlator falls off with a rate given by the Coulomb energy of an infinitely heavy charge. At high temperature, the screening mass approaches πT /2, and this in the presence of a mass gap. The fractional Matsubara frequency arises from the action of a pair of induced merons at high temperature that are localized over a range on the order of the meson Compton wavelength 1/m = √ π/g. We discuss the quenched approximation in this model, and comment on the possible relevance of some of these results to higher dimensions.