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We investigate $\beta$-functions of quantum gravity using dimensional regularisation. In contrast to minimal subtraction, a non-minimal renormalisation scheme is employed which is sensitive to power-law divergences from mass terms or…

High Energy Physics - Theory · Physics 2024-09-17 Yannick Kluth

The exact renormalization group equation for pure quantum gravity is derived for an arbitrary gauge parameter in the space-time dimension $d=4$. This equation is given by a non-linear functional differential equation for the effective…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Wataru Souma

We compute non-perturbative flow equations for the couplings of quantum gravity in fourth order of a derivative expansion. The gauge invariant functional flow equation for arbitrary metrics allows us to extract $\beta$-functions for all…

High Energy Physics - Theory · Physics 2022-03-24 Saswato Sen , Christof Wetterich , Masatoshi Yamada

The exact renormalization group equation for pure quantum gravity is used to derive the non-perturbative $\Fbeta$-functions for the dimensionless Newton constant and cosmological constant on the theory space spanned by the Einstein-Hilbert…

High Energy Physics - Theory · Physics 2010-04-06 M. Reuter , F. Saueressig

When general relativity is augmented by quadratic gravity terms, it becomes a renormalisable theory of gravity. This theory may admit a non-Gaussian fixed point as envisaged in the asymptotic safety program, rendering the theory trustworthy…

High Energy Physics - Theory · Physics 2019-11-06 Jean-Luc Lehners , K. S. Stelle

The gravitational asymptotic safety program envisions a high-energy completion of the gravitational interactions by an interacting renormalization group fixed point, the Reuter fixed point. The primary tool for investigating this scenario…

High Energy Physics - Theory · Physics 2023-03-01 Frank Saueressig

We prove the renormalizability of quantum gravity near two dimensions. The successful strategy is to keep the volume preserving diffeomorphism as the manifest symmetry of the theory. The general covariance is recovered by further imposing…

High Energy Physics - Theory · Physics 2009-10-28 Yoshihisa Kitazawa

The scaling behaviour of euclidean quantum gravity at an asymptotically safe critical point is studied by means of the exact renormalisation group. Gauge independence is ensured via a specific parameterisation of metric fluctuations…

High Energy Physics - Theory · Physics 2015-11-17 Kevin Falls

The asymptotic safety program strives for a consistent description of gravity as a non-perturbatively renormalizable quantum field theory. In this framework the gravitational interactions are encoded in a renormalization group flow…

General Relativity and Quantum Cosmology · Physics 2019-01-08 Frank Saueressig , Giulia Gubitosi , Chris Ripken

These lecture notes provide a pedagogical introduction to a specific continuum implementation of the Wilsonian renormalization group, the effective average action. Its general properties and, in particular, its functional renormalization…

High Energy Physics - Theory · Physics 2007-08-10 Martin Reuter , Frank Saueressig

We find considerable evidence supporting the conjecture that four-dimensional Quantum Einstein Gravity is ``asymptotically safe'' in Weinberg's sense. This would mean that the theory is likely to be nonperturbatively renormalizable and thus…

High Energy Physics - Theory · Physics 2009-11-07 O. Lauscher , M. Reuter

We explore the nonperturbative renormalization group flow of Quantum Einstein Gravity (QEG) on an infinite dimensional theory space. We consider "conformally reduced" gravity where only fluctuations of the conformal factor are quantized and…

High Energy Physics - Theory · Physics 2009-09-02 Martin Reuter , Holger Weyer

Real-Space renormalization group techniques are developed for tackling large curvature fluctuations in quantum gravity. Within cells of invariant volume $a^4$, only certain types of fluctuations are allowed. Normal coordinates are used to…

High Energy Physics - Theory · Physics 2016-10-21 H. S. Sharatchandra

We study fixed points of quantum gravity with renormalisation group methods, and a procedure to remove convergence-limiting poles from the flow. The setup is tested within the $f(R)$ approximation for gravity by solving exact recursive…

General Relativity and Quantum Cosmology · Physics 2019-07-03 Kevin G. Falls , Daniel F. Litim , Jan Schröder

We construct a novel Wetterich-type functional renormalization group equation for gravity which encodes the gravitational degrees of freedom in terms of gauge-invariant fluctuation fields. Applying a linear-geometric approximation the…

High Energy Physics - Theory · Physics 2015-04-30 Maximilian Demmel , Frank Saueressig , Omar Zanusso

We discuss the renormalization of Einstein-Hilbert's gravity in $d=2+\epsilon$ dimensions. We show that the application of the path-integral approach leads naturally to scheme- and gauge-independent results on-shell, but also gives a…

High Energy Physics - Theory · Physics 2024-02-28 Riccardo Martini , Dario Sauro , Omar Zanusso

Building a consistent Quantum Theory of Gravity is one of the most challenging aspects of modern theoretical physics. In the past couple of years, new attempts have been made along the path of ``asymptotic safety'' through the use of Exact…

High Energy Physics - Theory · Physics 2009-11-10 Daniele Perini

We evaluate the quantum corrections of the Einstein-Hilbert action with boundaries in the $2+\epsilon$ dimensional expansion approach. We find the Einstein-Hilbert action with boundaries to be renormalizable to the one loop order. We…

High Energy Physics - Theory · Physics 2010-11-01 T. Aida , Y. Kitazawa

Physics in the vicinity of an ultraviolet stable fixed point of a quantum field theory is parametrized by a renormalization group invariant macroscopic length scale, the correlation length $\xi,$ with the quantum effective action a function…

Astrophysics · Physics 2007-05-23 Vipul Periwal

We establish the functional Renormalization Group as an exploratory tool to investigate a possible phase transition between a pre-geometric discrete phase and a geometric continuum phase in quantum gravity. In this paper, based on the…

General Relativity and Quantum Cosmology · Physics 2014-12-03 Astrid Eichhorn , Tim Koslowski