Black Hole entropy for two higher derivative theories of gravity

Understand

The dark energy issue is focusing the attention of an incresing number of physicists all over the world.

• Among the possible alternatives in order to explain what as been named the "Mystery of the Millennium" are the so-called Modified Theories of Gravity.
• A crucial test for such models is represented by the existence and (if this is the case) the properties of their black hole solutions.
• Nowadays, to our knowledge, only two non-trivial, spherically symmetric, solutions with vanishing cosmological constant are known by Barrow & Clifton (2005) and Deser, Sarioglu & Tekin (2008).