Topological Charge Correlators, Spectral Bounds, and Contact Terms

TL;DR

This paper investigates the structure of topological charge fluctuations in the QCD vacuum, focusing on spectral negativity and contact terms, and explores their physical origins through illustrative examples.

Contribution

It provides a detailed analysis of the spectral and contact term properties of topological charge correlators in QCD, highlighting their physical implications.

Findings

Spectral negativity constrains charge fluctuation structures.

Presence of positive contact terms influences correlator behavior.

Examples illustrate the physical origin of these properties.

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 $x\neq 0$ and the presence of a positive contact term. Some examples are considered which illustrate the physical origin of these properties.