Elusive anomalies

TL;DR

This paper reviews ambiguities in calculating trace anomalies, highlighting cases where lowest-order perturbation is insufficient, which may clarify recent conflicting findings in the field.

Contribution

It identifies situations where simple perturbative methods fail to unambiguously determine trace anomalies, emphasizing the need for more careful analysis.

Findings

Highlighting ambiguities in trace anomaly calculations

Identifying cases where lowest-order perturbation is inadequate

Clarifying potential sources of contradictory results

Abstract

Usually, in order to compute an anomaly (be it chiral or trace) with a perturbative method, the lowest significant order is sufficient. With the help of gauge or diffeomorphism invariance it uniquely identifies the anomaly. This note is a short review of the ambiguities that arise in the calculation of trace anomalies, and is meant, in particular, to signal cases in which the lowest perturbative order is not enough to unambiguously identify a trace anomaly. This may shed light on some recent contradictory results.