Gauge-fixing ambiguities and gauge dependence of gauge-variant Schwinger-model correlation functions.

Abstract

Motivated by recent numerical studies of gauge-variant correlation functions in (3+1)-dimensional lattice QCD, we examine quark and photon correlation functions in the massless Schwinger model on $D=1+1$ Minkowski space ${M}^{2}$. Quantizing ${\mathrm{QED}}_{{M}^{2}}$ in covariant gauges, we find that (i) the effective quark mass depends on the covariant gauge parameter $\ensuremath{\xi}$ and (ii) gauge-fixing ambiguities modify operator-product-expansion coefficients computed by matching nonperturbative quark correlation functions.