0912.1433 (Ümit Ertem et al.)

Generalized Chern-Simons Modified Gravity in First-Order Formalism    [PDF]

Ümit Ertem, Özgür Aç\ik

We propose a generalization of Chern-Simons (CS) modified gravity in first-order formalism. CS modified gravity action has a term that comes from the chiral anomaly which is Pontryagin invariant. First-order CS modified gravity is a torsional theory and in a space-time with torsion the chiral anomaly includes a torsional topological term called Nieh-Yan invariant. We generalize the CS modified gravity by adding the Nieh-Yan term to the action and find the effective theory. We compare the generalized theory with the first-order CS modified gravity and comment on the similarities and differences.

View original: http://arxiv.org/abs/0912.1433