On Gauss Bonnet black hole entropy

We investigate the entropy of black holes in Gauss Bonnet and Lovelock gravity using the Noether charge approach, in which the entropy is given as the integral of a suitable (n - 2) form charge over the event horizon. We compare the results to those obtained in other approaches. We also comment on the appearance of negative entropies in some cases, and show that there is an additive ambiguity in the definition of the entropy which can be appropriately chosen to avoid this problem.