Symmetries and gravitational Chern-Simons Lagrangian terms

Understand

We consider some general consequences of adding pure gravitational Chern-Simons term to manifestly diff-covariant theories of gravity.

• Extending the result of a previous paper we enlarge the class of metrics for which the inclusion of a gCS term in the action does not affect solutions and corresponding physical quantities.
• In the case in which such solutions describe black holes (of general horizon topology) we show that the black hole entropy is also unchanged.
• We arrive at these conclusions by proving three general theorems and studying their consequences.