| Details: |
In addition to the gravitational (Newton's) constant, gravity theory in
four dimensions has three independent topological
coupling constants. In the Lagrangian, these show up as coefficients of
three topological densities, namely Nieh-Yan, Pontryagin and Euler. We
analyse the Hamiltonian theory of gravity based on a generalized
Lagrangian containing these three topological densities in addition to the
Hilbert-Palatini term. Based on the canonical analysis, we discuss how the
quantum theory of gravity might perceive these within various possible
quantization schemes. |