2003/11/30 by M. Reuter, H. Weyer · 4 citations
Physics and Astronomy · #hep-th #gr-qc
paper · pdf · doi:10.1103/physrevd.69.104022
published as Phys.Rev. D69 (2004) 104022 · LaTeX, 72 pages, no figures
arxiv created 2004/03/23 · arxiv updated 2009/12/01
A new framework for exploiting information about the renormalization group (RG) behavior of gravity in a dynamical context is discussed. The Einstein-Hilbert action is RG-improved by replacing Newton's constant and the cosmological constant by scalar functions in the corresponding Lagrangian density. The position dependence of G and Λ is governed by a RG equation together with an appropriate identification of RG scales with points in spacetime. The dynamics of the fields G and Λ does not admit a Lagrangian description in general. Within the Lagrangian formalism for the gravitational field they have the status of externally prescribed ``background'' fields. The metric satisfies an effective Einstein equation similar to that of Brans-Dicke theory. Its consistency imposes severe constraints on allowed backgrounds. In the new RG-framework, G and Λ carry energy and momentum. It is tested in the setting of homogeneous-isotropic cosmology and is compared to alternative approaches where the fields G and Λ do not carry gravitating 4-momentum. The fixed point regime of the underlying RG flow is studied in detail.