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Main Author: Upadhyay, Shivam
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2501.07136
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author Upadhyay, Shivam
author_facet Upadhyay, Shivam
contents We revisit the gravitational boundary action at null infinity of asymptotically flat spacetimes. We fix the corner ambiguities in the boundary action by using the constraint that (exponential of) the on-shell action leads to tree-level 5-point amplitude in eikonal approximation in a generic supertranslated vacuum. The subleading soft graviton theorem follows naturally from the on-shell action when the BMS group is extended to include superrotations. An infinite tower of Goldstone modes is proposed by `generalizing' the Geroch tensor to incorporate a set of divergence-free symmetric traceless tensors on the sphere. This generalization leads to $\text{sub}^{n}$-leading soft insertions in the tree-level $\mathcal{S}$ matrix, thus paving the way to understanding the infinite tower of tree-level symmetries within this framework.
format Preprint
id arxiv_https___arxiv_org_abs_2501_07136
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On symmetries of gravitational on-shell boundary action at null infinity
Upadhyay, Shivam
High Energy Physics - Theory
General Relativity and Quantum Cosmology
We revisit the gravitational boundary action at null infinity of asymptotically flat spacetimes. We fix the corner ambiguities in the boundary action by using the constraint that (exponential of) the on-shell action leads to tree-level 5-point amplitude in eikonal approximation in a generic supertranslated vacuum. The subleading soft graviton theorem follows naturally from the on-shell action when the BMS group is extended to include superrotations. An infinite tower of Goldstone modes is proposed by `generalizing' the Geroch tensor to incorporate a set of divergence-free symmetric traceless tensors on the sphere. This generalization leads to $\text{sub}^{n}$-leading soft insertions in the tree-level $\mathcal{S}$ matrix, thus paving the way to understanding the infinite tower of tree-level symmetries within this framework.
title On symmetries of gravitational on-shell boundary action at null infinity
topic High Energy Physics - Theory
General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2501.07136