IMSc Webinar

Generalized BMS symmetry and Double soft graviton theorems.

Anupam A.H.

IMSc, Chennai

We show that the Ward identities corresponding to generalized BMS
symmetries in scattering states built around degenerate vacua labeled by
supertranslations and Diff(S^{2}) charges are equivalent to a a special
class of double soft graviton theorems called consecutive double soft
graviton theorems. We further argue that such double soft graviton theorems
can be realized by considering nested Ward identities constructed out of
two generalized BMS charges. In order to extend the analysis of the
relationship of generalized BMS charge algebra with double soft theorems
when the external states are massive, we consider the algebra of the
generalized BMS vector fields at timelike infinity. We show that the vector
fields at timelike infinity close under the modified Lie bracket proposed
by Barnich et al.
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