Topological susceptibility in full QCD: lattice results versus the prediction from the QCD partition function with granularity

TL;DR

This paper compares recent lattice QCD data on topological susceptibility with theoretical predictions based on the QCD partition function, revealing a surprisingly large chiral condensate in two-flavor QCD.

Contribution

It introduces a refined theoretical model incorporating granularity in the QCD partition function to better match lattice data on topological susceptibility.

Findings

Lattice data from multiple groups show consistent quark mass dependence.

Theoretical predictions with granularity align well with lattice results.

The chiral condensate derived is unexpectedly large.

Abstract

Recent lattice data from CP-PACS, UKQCD, SESAM/TXL and the Pisa group regarding the quark mass dependence of the topological susceptibility in 2-flavour QCD are compared to each other and to theoretical expectations. The latter get specified by referring to the QCD finite-volume partition function with ``granularity'' which accounts for the entropy brought by instantons and anti-instantons. The chiral condensate in $N_f=2$ QCD, if determined by this method, turns out surprisingly large.