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Résumé |
We investigate the standard and dual BMS supertranslation generators on the black
hole horizon and draw some conclusions about black hole physics. Recently, it has
been shown that in addition to the conventional BMS supertranslation symmetries,
there exists another infinite set of magnetic asymptotic symmetries that are
referred to as dual BMS supertranslations. We show that the Dirac bracket between
these generators exhibits a central term when the parameter functions have
singularities in the complex stereographical coordinates on the sphere. Such
singularities are related to Dirac-string-like configurations in the bulk, and
should therefore be included in the set of acceptable transformations. We then
demonstrate that this anomalous central term can be removed by including an
appropriate gravitational Chern-Simons theory on the horizon. This implies that
consistency of the asymptotic symmetry algebra requires a new structure on the
horizon. |
