Angular momentum at null infinity in higher dimensions

TL;DR

This paper defines angular momentum at null infinity in higher-dimensional spacetimes, demonstrating it is well-defined and transforms covariantly under the Poincare group, unlike in four dimensions where supertranslations cause ambiguities.

Contribution

It introduces a new, unambiguous definition of angular momentum at null infinity in higher dimensions, avoiding supertranslation issues present in four-dimensional cases.

Findings

Angular momentum at null infinity in higher dimensions is well-defined.

The asymptotic symmetry group is the Poincare group in higher dimensions.

The defined angular momentum transforms covariantly under Poincare transformations.

Abstract

We define the angular momentum at null infinity in higher dimensions. The asymptotic symmetry at null infinity becomes the Poincare group in higher dimensions. This fact implies that the angular momentum can be defined without any ambiguities such as supertranslation in four dimensions. Indeed we can show that the angular momentum in our definition is transformed covariantly with respect to the Poincare group.