2010/03/19 by C. Wetterich
Physics and Astronomy · #Black Holes and Theoretical Physics #Cosmology and Gravitation Theories #Relativity and Gravitational Theory #astro-ph.CO #hep-th
paper · pdf · doi:10.1103/physrevd.81.103508
published as Phys.Rev.D81:103508,2010 · 28 pages
arxiv created 2010/03/19 · openalex publication_date 2010/05/05 · arxiv updated 2010/05/25 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We investigate consequences of an ultraviolet fixed point in quantum gravity for the cosmological constant. For this purpose we perform dimensional reduction of a general dilatation-symmetric effective action \ensuremathΓ in dimension d>4 to an effective four-dimensional theory of gravity with a dilaton field. We find a stable flat phase in the space of the extrema of \ensuremathΓ which results in a vanishing four-dimensional cosmological constant \ensuremathΛ. In order to understand the self-tuning mechanism leading to \ensuremathΛ=0 we discuss in detail the most general warped geometries with maximal four-dimensional symmetry and SO(d\ensuremath-4) isometry of internal space. While the solutions of the d-dimensional field equations admit singular spaces with arbitrary \ensuremathΛ, the extremum condition for \ensuremathΓ imposes additional restrictions which result in \ensuremathΛ=0. In cosmology, the dilatation-symmetric fixed point may only be reached for asymptotic time t\ensuremath→\ensuremath∞. At finite t dilatation anomalies result in an effective potential and mass for the pseudodilaton or cosmon and in dark energy.