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We describe a functional renormalization group-based method to search for `$C$-like' functions with properties similar to that in 2D conformal field theory. It exploits the mode counting properties of the effective average action and is…

High Energy Physics - Theory · Physics 2015-02-12 Daniel Becker , Martin Reuter

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

Theoretical possibilities of models of gravity with dynamical signature are discussed. The different scenarios of the signature change are proposed in the framework of Einstein-Cartan gravity. We consider, subsequently, the dynamical…

General Relativity and Quantum Cosmology · Physics 2022-09-13 S. Bondarenko

The methods of the renormalization group and the $\varepsilon$-expansion are applied to quantum gravity revealing the existence of an asymptotically safe fixed point in spacetime dimensions higher than two. To facilitate this, physical…

High Energy Physics - Theory · Physics 2018-01-04 Kevin Falls

We investigate the problem of metric fluctuations in the presence of the vacuum fluctuations of matter fields and critically assess the usual assertion that vacuum energy implies a Planckian cosmological constant. A new stochastic classical…

General Relativity and Quantum Cosmology · Physics 2008-06-19 Charles H. -T. Wang , Paolo M. Bonifacio , Robert Bingham , J. Tito Mendonca

This is an introduction to asymptotically safe quantum gravity, explaining the main idea of asymptotic safety and how it could solve the problem of predictivity in quantum gravity. In the first part, the concept of an asymptotically safe…

General Relativity and Quantum Cosmology · Physics 2020-03-03 Astrid Eichhorn

The effective potential of the conformal factor in the effective average action approach to Quantum Einstein Gravity is discussed. It is shown, without invoking any truncation or other approximations, that if the theory has has a…

High Energy Physics - Theory · Physics 2011-08-17 Jan-Eric Daum , Martin Reuter

Asymptotic Safety is a promising framework towards the understanding, in a non-perturbative way, of Quantum Gravity. It treats the Newton's constant G_N and the cosmological constant \Lambda as running coupling of an effective action. At…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-17 Vasilios Zarikas

We study the nonperturbative formulation of quantum gravity defined via Euclidean dynamical triangulations (EDT) in an attempt to make contact with Weinberg's asymptotic safety scenario. We find that a fine-tuning is necessary in order to…

High Energy Physics - Theory · Physics 2017-09-20 J. Laiho , S. Bassler , D. Coumbe , D. Du , J. T. Neelakanta

Over the last years the Asymptotic Safety program has matured into a serious candidate for a quantum theory of gravity compatible with observations. The rapid technical progress in computing renormalisation group flows for gravity and…

High Energy Physics - Theory · Physics 2020-01-08 Benjamin Knorr , Chris Ripken , Frank Saueressig

Asymptotic safety is an attractive scenario for the dynamics of quantum spacetime. Here, we work from a phenomenologically motivated point of view and emphasize that a viable dynamics for quantum gravity in our universe must account for the…

General Relativity and Quantum Cosmology · Physics 2016-05-12 Pietro Donà , Astrid Eichhorn , Peter Labus , Roberto Percacci

We study the quantum properties of the three-dimensional higher derivative gravity. In particular we calculate the running of the gravitational and cosmological constants. The flow of these couplings shows that there exist both Gaussian and…

High Energy Physics - Theory · Physics 2015-06-05 Nobuyoshi Ohta

We perform a general computation of the off-shell one-loop divergences in Einstein gravity, in a two-parameter family of path integral measures, corresponding to different ways of parametrizing the graviton field, and a two-parameter family…

High Energy Physics - Theory · Physics 2016-07-20 N. Ohta , R. Percacci , A. D. Pereira

Within the Asymptotic Safety scenario, we discuss whether Quantum Einstein Gravity (QEG) can give rise to a semi-classical regime of propagating physical gravitons (gravitational waves) governed by an effective theory which complies with…

High Energy Physics - Theory · Physics 2015-06-22 Daniel Becker , Martin Reuter

In the context of gravity the Lagrangian and Hamiltonian formalisms have been developed largely independently, emphasizing renormalization and quantization, respectively. The formalisms use a different methodology to distinguish between…

High Energy Physics - Theory · Physics 2025-10-29 Renata Ferrero

We discuss general momentum-dependent field redefinitions in the context of quantum-gravitational scattering amplitudes in general, and Asymptotic Safety in particular. Implementing such redefinitions at the lowest curvature order, we can…

High Energy Physics - Theory · Physics 2024-01-24 Benjamin Knorr

Using the background-metric independence for the traceless mode as well as the conformal mode, 4D quantum gravity is described as a quantum field theory defined on a non-dynamical background-metric. The measure then induces an action with 4…

High Energy Physics - Theory · Physics 2009-10-31 Ken-ji Hamada , Fumihiko Sugino

Being interested in the compatibility of Asymptotic Safety with Hilbert space positivity (unitarity), we consider a local truncation of the functional RG flow which describes quantum gravity in $d>2$ dimensions and construct its limit of…

High Energy Physics - Theory · Physics 2016-03-09 Andreas Nink , Martin Reuter

We study the renormalizable quantum gravity formulated as a perturbed theory from conformal field theory (CFT) on the basis of conformal gravity in four dimensions. The conformal mode in the metric field is managed non-perturbatively…

High Energy Physics - Theory · Physics 2009-11-10 Ken-ji Hamada

Asymptotic Safety (AS) Paradigm is an interesting set of ideas and methods towards a meaningful quantization of Gravity. A brief review of phenomenological consequences in the context of AS regarding cosmology with emphasis on dark energy…

General Relativity and Quantum Cosmology · Physics 2024-10-11 Vasilios Zarikas