Spin tensor and pseudo-gauges: from nuclear collisions to gravitational physics

  • The relativistic treatment of spin is a fundamental subject which has an old history. In various physical contexts it is necessary to separate the relativistic total angular momentum into an orbital and spin contribution. However, such decomposition is affected by ambiguities since one can always redefine the orbital and spin part through the so-called pseudo-gauge transformations. We analyze this problem in detail by discussing the most common choices of energy-momentum and spin tensors with an emphasis on their physical implications, and study the spin vector which is a pseudo-gauge invariant operator. We review the angular momentum decomposition as a crucial ingredient for the formulation of relativistic spin hydrodynamics and quantum kinetic theory with a focus on relativistic nuclear collisions, where spin physics has recently attracted significant attention. Furthermore, we point out the connection between pseudo-gauge transformations and the different definitions of the relativistic center of inertia. Finally, we consider the Einstein–Cartan theory, an extension of conventional general relativity, which allows for a natural definition of the spin tensor.

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Author:Enrico SperanzaORCiDGND, Nora WeickgenanntORCiDGND
Parent Title (English):The European physical journal A
Place of publication:Berlin ; Heidelberg
Document Type:Article
Date of Publication (online):2021/05/03
Date of first Publication:2021/05/03
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2022/10/20
Article Number:155
Page Number:25
First Page:1
Last Page:25
Open Access funding enabled and organized by Projekt DEAL.
Institutes:Physik / Physik
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik
Licence (German):License LogoCreative Commons - Namensnennung 4.0