Chiral condensate in nf=2 QCD from the Banks-Casher relation

TL;DR

This study uses the Banks-Casher relation to directly measure the chiral condensate in two-flavor QCD, analyzing lattice data across multiple spacings and pion masses to confirm spontaneous chiral symmetry breaking.

Contribution

It provides a direct lattice calculation of the chiral condensate in nf=2 QCD using the mode number approach with improved Wilson fermions.

Findings

Non-zero eigenmode density near zero indicates chiral symmetry breaking.

Continuum and chiral extrapolations yield a non-zero chiral condensate.

Results are consistent across different lattice spacings and pion masses.

Abstract

Exploiting the Banks-Casher relation, we present a direct determination of the chiral condensate in two-flavor QCD, computing the mode number of the O(a)-improved Wilson-Dirac operator below various cutoffs. We make use of CLS-configurations with three different lattice spacings in the range of 0.05-0.08 fm and pion masses down to 190 MeV. Our data indicate a non-zero density of eigenmodes near the origin and hence points to spontaneous chiral symmetry breaking. We extrapolate our results to the continuum and chiral limit to give a result for the chiral condensate.