2008/09/30 by Ethan Dyer, Kurt Hinterbichler · 8 citations
Physics and Astronomy · #Black Holes and Theoretical Physics #Cosmology and Gravitation Theories #Noncommutative and Quantum Gravity Theories #gr-qc #hep-th
paper · pdf · doi:10.1103/physrevd.79.024028
published as Phys.Rev.D79:024028,2009 · 54 pages, 2 figures. Several typos corrected, references added. Version appearing in PRD
arxiv created 2009/01/28 · openalex publication_date 2009/01/28 · arxiv updated 2010/04/28 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We discuss the criteria that must be satisfied by a well-posed variational principle. We clarify the role of Gibbons-Hawking-York type boundary terms in the actions of higher derivative models of gravity, such as F(R) gravity, and argue that the correct boundary terms are the naive ones obtained through the correspondence with scalar-tensor theory, despite the fact that variations of normal derivatives of the metric must be fixed on the boundary. We show in the case of F(R) gravity that these boundary terms reproduce the correct Arnowitt-Deser-Misner energy in the Hamiltonian formalism, and the correct entropy for black holes in the semiclassical approximation.