Chirally improving Wilson fermions

TL;DR

This paper proposes a method to enhance chiral symmetry and continuum limit approach in lattice QCD by averaging correlators from Wilson fermions with opposite signs, using twisted-mass QCD to avoid zero-mode issues.

Contribution

It introduces a technique of averaging correlators from Wilson fermions with opposite signs and recommends twisted-mass QCD for practical computations to improve chiral behavior.

Findings

Averaging correlators improves chiral symmetry properties.

Twisted-mass QCD at specific angles simplifies calculations.

Method enhances approach to continuum limit in lattice QCD.

Abstract

It is possible to improve the chiral behaviour and the approach to the continuum limit of correlation functions in lattice QCD with standard and twisted Wilson fermions by taking arithmetic averages of correlators computed in theories regularized with Wilson terms of opposite sign. To avoid the problem of the spurious zero-modes of the Wilson--Dirac operator, twisted-mass lattice QCD should be used for the actual computation of the correlators taking part in the averages. A particularly useful choice for the twisting angle is $\pm\pi/2$ where many physical quantities (e.g. masses and zero-momentum matrix elements) are automatically improved with no need of averaging.