Short distance current correlators: Comparing lattice simulations to the instanton liquid

TL;DR

This paper compares lattice QCD correlators with instanton liquid models, revealing qualitative similarities at low energies and distances, and highlighting effects of quenched artifacts in scalar channels.

Contribution

It provides a detailed comparison between lattice QCD simulations and instanton liquid models for current correlators, emphasizing qualitative and quantitative agreements.

Findings

Qualitative resemblance between lattice correlators and instanton models at low energies.

Quantitative agreement in vector and axial vector channel differences.

Identification of quenched finite volume artifacts in scalar correlators.

Abstract

Point to point correlators of currents are computed in quenched QCD using a chiral lattice fermion action, the overlap action. I compare correlators made of exact quark propagators with correlators restricted to low (less than 500 MeV) eigenvalue eigenmodes of the Dirac operator. In many cases they show qualitative resemblence (typically at small values of the quark mass and distances larger than 0.4 fm) and they differ qualitatively at larger quark masses or at very short distance. Lattice results are in qualitative agreement (and in the difference of vector and axial vector channels, quantitative agreement) with the expectations of instanton liquid models. The scalar channel shows the effects of a quenched finite volume zero mode artifact, a negative correlator.