Lovelock action with nonsmooth boundaries

Understand

We examine the variational problem in Lovelock gravity when the boundary contains timelike and spacelike segments nonsmoothly glued.

• We show that two kinds of contributions have to be added to the action.
• The first one is associated to the presence of a boundary in every segment and it depends on intrinsic and extrinsic curvatures.
• We can think of this contribution as adding a total derivative to the usual surface term of Lovelock gravity.