A note on the exact lattice chiral symmetry in the overlap formalism

TL;DR

This paper demonstrates that the overlap formalism's auxiliary fermion system inherently possesses an exact chiral symmetry, connecting the covariant anomaly with the axial anomaly in lattice gauge theory.

Contribution

It shows how the symmetry of the auxiliary quantum fermion system induces exact chiral symmetry in the overlap formalism, clarifying the relation between covariant and axial anomalies.

Findings

Exact chiral symmetry is induced by the auxiliary fermion system.

Explicit expression for the covariant gauge current in the overlap formalism.

Connection established between covariant anomaly and axial anomaly.

Abstract

Using the grassman-number-integral representation of the vacuum overlap formula, it is shown that the symmetry of the auxiliary quantum fermion system in the overlap formalism induces exact chiral symmetry of the action of the type given by Luscher under the chiral transformation $\delta \psi_n = \gamma_5(1-a D)\psi_n$ and $ \delta \bar \psi_n = \bar \psi_n \gamma_5$. With this relation, we consider the connection between the covariant form of the anomaly discussed in the context of the overlap formula and the axial anomaly associated to the exact chiral symmetry in the action formalism. The covariant gauge current in the overlap formalism is translated to the action formalism and its explicit expression is obtained.