Generalized second law at linear order for actions that are functions of Lovelock densities

TL;DR

This paper demonstrates that in theories with actions as functions of Lovelock densities, a locally increasing entropy exists at linear order for perturbations of Killing horizons, extending to semiclassical matter fields.

Contribution

It establishes a generalized second law for such theories, including semiclassical effects, at linear order perturbations.

Findings

Existence of a locally increasing entropy for linearized perturbations.

Proof of a generalized second law including semiclassical matter.

Applicability to theories with actions as functions of Lovelock densities.

Abstract

In this article we consider the second law of black holes (and other causal horizons) in theories where the gravitational action is an arbitrary function of the Lovelock densities. We show that there exists an entropy which increases locally, for linearized perturbations to regular Killing horizons. In addition to a classical increase theorem, we also prove a generalized second law for semiclassical, minimally-coupled matter fields.