Null boundary terms for Lanczos-Lovelock gravity

TL;DR

This paper derives new null boundary terms for Lanczos-Lovelock gravity under Dirichlet conditions, filling a gap in the literature and providing specific results for Gauss-Bonnet gravity.

Contribution

It presents the first derivation of null boundary terms for Lanczos-Lovelock gravity based solely on the boundary variation structure.

Findings

Boundary terms for Lanczos-Lovelock gravity are derived.

Null boundary term for Gauss-Bonnet gravity is provided.

First-time derivation of these boundary terms in the literature.

Abstract

We derive boundary terms appropriate for the general Lanczos-Lovelock action on a null boundary, when Dirichlet boundary conditions are imposed. We believe that these boundary terms have been derived for the first time in the literature. In this derivation, we rely only on the structure of the boundary variation of the action for Lanczos-Lovelock gravity. We also provide the null boundary term for Gauss-Bonnet gravity separately.