Publication

Noether Theorems and Quantum Anomalies

Tudor Ratiu
2017
Journal Articles

Résumé

A quantum anomaly is the breaking of symmetry with respect to some transformations after the quantization of a classical Hamiltonian or Lagrangian system. It is shown that both the Noether theorems (including their infinite-dimensional versions) and the explanation of the origin of quantum anomalies can be obtained by using similar formulas for derivatives of functions whose values are measure in the former case and pseudomeasures in the latter.

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https://infoscience.epfl.ch/entities/publication/58ad56c7-9203-4a54-94e6-1613f908ad5d

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Tudor Ratiu
2017
Journal Articles

Résumé

Source officielle

https://infoscience.epfl.ch/entities/publication/58ad56c7-9203-4a54-94e6-1613f908ad5d

À propos de ce résultat

Concepts associés (32)

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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