On the Energy Issue for a Class of Modified Higher Order Gravity Black   Hole Solutions
  In the case of a large class of static spherically symmetric black hole solutions in higher order modified gravity models, an expression for the associated energy is proposed and identified as a quantity proportional to the constant of integration, which appears in the explicit solution. The identification is achieved making use of derivation of the First Law of black hole physics from the equations of motion, evaluating independently the Entropy via Wald method and the Hawking temperature via the tunneling method. Several non trivial examples are discussed, including a new topological higher derivative black hole solution. 
Guido Cognola, Olesya Gorbunova, Lorenzo Sebastiani and Sergio Zerbini
gr-qc hep-th