Brown-York charges at null boundaries
Brown-York charges at null boundaries
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DOI：
10.1007/jhep01(2022)029
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发表时间：
2022-01
影响因子：
5.4
通讯作者：
V. Chandrasekaran;E. Flanagan;I. Shehzad;A. Speranza
中科院分区：
文献类型：
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作者：
V. Chandrasekaran;E. Flanagan;I. Shehzad;A. Speranza
布朗-约克应力张量提供了一种在类时超曲面所限定的子区域中定义准局部引力荷的方法。我们考虑这个应力张量的推广零超曲面。这样的应力张量可以从广义相对论的壳分区作用量和Dirichlet变分原理推导出来，该变分原理将诱导的卡罗尔结构固定在零边界上。混合指数张量T i j的公式采取了一个非常简单的形式，显然是独立的辅助零矢量的选择在零表面，我们比较这个表达式与以前的建议为零布朗约克应力张量。作为零约束方程的结果，我们得到的应力张量满足关于从超曲面处的索具向量诱导的任何连接的协变守恒方程。对于协变作用于边界结构的变换，布朗-约克电荷与从Wald-Zoupas程序的一个版本构造的正则电荷相吻合。对于异常变换，收费不同的边界几何，我们明确验证一组与有限零超曲面的对称性的内在功能。讨论了零布朗约克应力张量在渐近平坦时空对称性和天体全息中的应用。
The Brown-York stress tensor provides a means for defining quasilocal gravitational charges in subregions bounded by a timelike hypersurface. We consider the generalization of this stress tensor to null hypersurfaces. Such a stress tensor can be derived from the on-shell subregion action of general relativity associated with a Dirichlet variational principle, which fixes an induced Carroll structure on the null boundary. The formula for the mixed-index tensor T i j takes a remarkably simple form that is manifestly independent of the choice of auxiliary null vector at the null surface, and we compare this expression to previous proposals for null Brown-York stress tensors. The stress tensor we obtain satisfies a covariant conservation equation with respect to any connection induced from a rigging vector at the hypersurface, as a result of the null constraint equations. For transformations that act covariantly on the boundary structures, the Brown-York charges coincide with canonical charges constructed from a version of the Wald-Zoupas procedure. For anomalous transformations, the charges differ by an intrinsic functional of the boundary geometry, which we explicity verify for a set of symmetries associated with finite null hyper-surfaces. Applications of the null Brown-York stress tensor to symmetries of asymptotically flat spacetimes and celestial holography are discussed.