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Charges in the Extended BMS Algebra: Definitions and Applications

by M. Porrati

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Submission summary

Authors (as registered SciPost users): Massimo Porrati
Submission information
Preprint Link: scipost_202012_00003v1  (pdf)
Date accepted: 2021-01-29
Date submitted: 2020-12-02 07:17
Submitted by: Porrati, Massimo
Submitted to: SciPost Physics Proceedings
Proceedings issue: 4th International Conference on Holography, String Theory and Discrete Approach in Hanoi (STRHAN2020)
Ontological classification
Academic field: Physics
  • High-Energy Physics - Theory
Approach: Theoretical


This is a review of selected topics from recent work on symmetry charges in asymptotically flat spacetime done by the author in collaboration with U. Kol and R. Javadinezhad. First we reinterpret the reality constraint on the boundary graviton as the gauge fixing of a new local symmetry, called dual supertranslations. This symmetry extends the BMS group and bears many similarities to the dual (magnetic) gauge symmetry of electrodynamics. We use this new gauge symmetry to propose a new description of the TAUB-NUT space that does not contain closed time-like curves. Next we summarize progress towards the definition of Lorentz and super-Lorentz charges that commute with supertranslations and with the soft graviton mode.

Author comments upon resubmission

Clarifications after eq. (7) and (13) on the definition and meaning of gauge charges.
The limit due to the new gauge symmetry being defined only asymptotically is made more explicit in the third bullet point after (13)

List of changes

Clarifications after eq. (7) and (13) on the definition and meaning of gauge charges and observables.

Published as SciPost Phys. Proc. 4, 005 (2021)

Reports on this Submission

Anonymous Report 1 on 2021-1-14 (Invited Report)

  • Cite as: Anonymous, Report on arXiv:scipost_202012_00003v1, delivered 2021-01-14, doi: 10.21468/SciPost.Report.2413


One of the requested changes (boundary conditions necessary for the existence of topological charges) has been addressed. The request for a physical explanation of the complex gauge transformation in real terms (especially for an observer) has not been addressed. As explained in the first report, the proceedings is clearly written. Since the authors plans on submitting a further paper on the topic, the unaddressed suggestions can be kept for further research. This proceedings summarizes past research by the author.

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