Chiral Anomaly in Lattice QCD with Twisted Mass Wilson Fermion

TL;DR

This paper investigates the chiral anomaly in lattice QCD using Osterwalder-Seiler twisted mass Wilson fermions, demonstrating improved approach to the chiral limit and explicit cancellation of parity-violating terms at finite lattice spacing.

Contribution

It provides a detailed study of the flavor singlet axial Ward identity with twisted mass Wilson fermions, showing advantages over other improved actions in approaching the chiral limit.

Findings

Better approach to the chiral limit compared to O(a) and O(a^2) improved actions.

Explicit cancellation of parity-violating terms up to O(g^2).

Validation of the Ward identity at finite volume and lattice spacing.

Abstract

The flavour singlet axial Ward identity with Osterwalder-Seiler twisted mass Wilson fermion action is studied on a finite lattice, with finite fermion mass and the Wilson parameter r up to 1. Approach to the infinite volume chiral limit and emergence of the anomaly is significantly better than that obtained with O(a) and O(a^2) improved fermion actions. We have shown explicitly that up to O(g^2), parity violating terms cancel in the Ward identity even at finite volume and finite lattice spacing.