Topological Charge Correlators, Spectral Bounds, and Contact Terms

Abstract

The structure of topological charge fluctuations in the QCD vacuum is strongly restricted by the spectral negativity of the Euclidean 2-point correlator for $x\ne 0$ and the presence of a positive contact term. Some examples are considered which illustrate the physical origin of these properties.

Comments: Lattice 2002 Conference Proceedings