Publication

Anomalies from the covariant derivative expansion

Timothy Cohen
2023
Journal Articles

Résumé

We revisit the calculation of chiral anomalies for global and gauge symmetries in the framework of the covariant derivative expansion (CDE). Due to the presence of UV divergences, the result is an ambiguous quantity that depends on the regularization procedure and the renormalization scheme. We introduce a class of regulators that facilitate a straightforward evaluation of the anomaly exclusively in d = 4 spacetime dimensions using the CDE methodology. We derive a master formula for the anomaly that integrates various known results into a unified framework.

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https://infoscience.epfl.ch/entities/publication/4befbcb8-20ac-4dbb-829c-8733e32162aa

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Timothy Cohen
2023
Journal Articles

Résumé

Source officielle

https://infoscience.epfl.ch/entities/publication/4befbcb8-20ac-4dbb-829c-8733e32162aa

À propos de ce résultat

Proximité ontologique

Physique

Théorie quantique des champs: Théorie quantique des champs

Concepts associés (19)

Anomalie (physique)

En théorie quantique des champs, on dit qu'une symétrie de la théorie possède une anomalie (ou que la symétrie est anormale) lorsqu'elle est une invariance classique au niveau de l'action mais qu'elle est brisée une fois que la théorie est quantifiée. Plus précisément une anomalie survient lorsque le courant de Noether est conservé au niveau classique mais que les interactions quantiques brisent cette conservation. Cet article présente les différents types d'anomalies que l'on peut rencontrer en physique théorique.

Gauge anomaly

In theoretical physics, a gauge anomaly is an example of an anomaly: it is a feature of quantum mechanics—usually a one-loop diagram—that invalidates the gauge symmetry of a quantum field theory; i.e. of a gauge theory. All gauge anomalies must cancel out. Anomalies in gauge symmetries lead to an inconsistency, since a gauge symmetry is required in order to cancel degrees of freedom with a negative norm which are unphysical (such as a photon polarized in the time direction). Indeed, cancellation occurs in the Standard Model.

Gravitational anomaly

In theoretical physics, a gravitational anomaly is an example of a gauge anomaly: it is an effect of quantum mechanics — usually a one-loop diagram—that invalidates the general covariance of a theory of general relativity combined with some other fields. The adjective "gravitational" is derived from the symmetry of a gravitational theory, namely from general covariance. A gravitational anomaly is generally synonymous with diffeomorphism anomaly, since general covariance is symmetry under coordinate reparametrization; i.

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