The Schwinger Model and Perturbative Charge Screening

Abstract

\noindent The well-known exact solution of the massless Schwinger model can be simply obtained by perturbing around a vacuum without the Dirac sea of filled negative energy states. The unusual vacuum structure changes the sign of the $i\epsilon$ prescription at the negative energy pole of the free fermion propagator. Consequently, all convergent fermion loop integrals vanish. The logarithmically divergent two-point loop gives a mass $e/\sqrt\pi$ to the photon, which turns into the free pointlike boson of the Schwinger model. We discuss the possiblity of using corresponding expansions to describe charge screening effects in the massive Schwinger model and the confinement phenomenon of QCD.