2015/09/16 by Martin Reuter, Gregor M. Schollmeyer · 1 citation
Physics and Astronomy · #gr-qc #hep-th
paper · pdf · doi:10.1016/j.aop.2015.12.004
73 pages, multiple figures
arxiv created 2015/09/16 · arxiv updated 2016/03/23
Searching for new non-perturbatively renormalizable quantum gravity theories, functional renormalization group (RG) flows are studied on a theory space of action functionals depending on the metric and the torsion tensor, the latter parameterized by three irreducible component fields. A detailed comparison with Quantum Einstein-Cartan Gravity (QECG), Quantum Einstein Gravity (QEG), and "tetrad-only" gravity, all based on different theory spaces, is performed. It is demonstrated that, over a generic theory space, the construction of a functional RG equation (FRGE) for the effective average action requires the specification of a metric on the infinite-dimensional field manifold as an additional input. A modified FRGE is obtained if this metric is scale-dependent, as it happens in the metric-torsion system considered.