Quantum Gravity and Higher Curvature Actions

Details Quantum Gravity and Higher Curvature Actions Quantum Gravity and Higher Curvature Actions

2006-06-23

arxiv.org/abs/hep-th/0606232v1

ECONFC0602061:03,2006; Int.J.Geom.Meth.Mod.Phys.4:25-52,2007

Physics

High Energy Physics

High Energy Physics - Theory

28 pages, based on a lecture course at the 42nd Karpacz Winter School of Theoretical Physics ``Current Mathematical Topics in

Scientific paper

10.1142/S0219887807001941

Effective equations are often useful to extract physical information from quantum theories without having to face all technical and conceptual difficulties. One can then describe aspects of the quantum system by equations of classical type, which correct the classical equations by modified coefficients and higher derivative terms. In gravity, for instance, one expects terms with higher powers of curvature. Such higher derivative formulations are discussed here with an emphasis on the role of degrees of freedom and on differences between Lagrangian and Hamiltonian treatments. A general scheme is then provided which allows one to compute effective equations perturbatively in a Hamiltonian formalism. Here, one can expand effective equations around any quantum state and not just a perturbative vacuum. This is particularly useful in situations of quantum gravity or cosmology where perturbations only around vacuum states would be too restrictive. The discussion also demonstrates the number of free parameters expected in effective equations, used to determine the physical situation being approximated, as well as the role of classical symmetries such as Lorentz transformation properties in effective equations. An appendix collects information on effective correction terms expected from loop quantum gravity and string theory.

Affiliated with

Also associated with

No associations

Rating

Quantum Gravity and Higher Curvature Actions does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Quantum Gravity and Higher Curvature Actions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Quantum Gravity and Higher Curvature Actions will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-529476