Stress Tensor on Null Boundaries

Understand

Using the Brown-York prescription for the definition of quasilocal gravitational energy-momentum tensor on a boundary and also complete canonical structure on a null boundary which has been found recently \cite{Aghapour:2018icu}, we propose a similar stress tensor on the null boundary.

• Then we exploit this stress tensor to compute the quasi-local energy and angular momentum for some well-known gravitational solutions.
• We have found that in addition to reference spacetime method for regularizing total energy, in the case of null boundary we can add a possible counterterm so avoiding embedding difficulties.