Axion field induces exact symmetry

TL;DR

This paper demonstrates that an artificial axion-induced symmetry for massive fermions remains consistent with standard regularization methods, even in curved spacetime, implying it has no anomaly in gauge or gravitational contexts.

Contribution

It shows that the axion-induced symmetry for massive fermions is anomaly-free and compatible with regularization, extending previous understanding from massless cases.

Findings

Axion-induced symmetry is consistent with standard regularization.

No anomaly in gauge or gravitational fields for the symmetry.

Implications for theta terms are discussed.

Abstract

While no regularization is consistent with the anomalous chiral symmetry which occurs for massless fermions, the artificial axion-induced symmetry for massive fermions is shown here to be consistent with a standard regularization, even in curved spacetime, so that it can be said to have no anomaly in gauge or gravitational fields. Implications for theta terms are pointed out.