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Corrections are computed to the classical static isotropic solution of general relativity, arising from non-perturbative quantum gravity effects. A slow rise of the effective gravitational coupling with distance is shown to involve a…

High Energy Physics - Theory · Physics 2008-11-26 Herbert W. Hamber , Ruth M. Williams

We introduce new techniques that can preserve unitarity of the system including ghost particles. Negative norms of the particles can be involved in zero-norm states by constraints of the physical space. These are useful to apply the…

General Relativity and Quantum Cosmology · Physics 2010-10-26 Hajime Isimori

This article contains a brief pedagogical introduction to various renormalization group related aspects of quantum gravity with an emphasis on the scale dependence of Newton's constant and on black hole physics.

High Energy Physics - Theory · Physics 2007-05-23 Martin Reuter

The possibility of a minimal physical length in quantum gravity is discussed within the asymptotic safety approach. Using a specific mathematical model for length measurements ("COM microscope") it is shown that the spacetimes of Quantum…

High Energy Physics - Theory · Physics 2008-11-26 Martin Reuter , Jan-Markus Schwindt

The quantum gauge general relativity is proposed in the framework of quantum gauge theory of gravity. It is formulated based on gauge principle which states that the correct symmetry for gravitational interactions should be gravitational…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Ning Wu

We study quantum gravity in $2+\epsilon$ dimensions in such a way to preserve the volume preserving diffeomorphism invariance. In such a formulation, we prove the following trinity: the general covariance, the conformal invariance and the…

High Energy Physics - Theory · Physics 2011-08-17 T. Aida , Y. Kitazawa , H. Kawai , M. Ninomiya

In grand unified theories with large numbers of fields, renormalization effects significantly modify the scale at which quantum gravity becomes strong. This in turn can modify the boundary conditions for coupling constant unification, if…

High Energy Physics - Phenomenology · Physics 2008-11-26 Xavier Calmet , Stephen D. H. Hsu , David Reeb

A scale--dependent effective action for gravity is introduced and an exact nonperturbative evolution equation is derived which governs its renormalization group flow. It is invariant under general coordinate transformations and satisfies…

High Energy Physics - Theory · Physics 2009-10-30 M. Reuter

Motivated by the conjecture that the cosmological constant problem could be solved by strong quantum effects in the infrared we use the exact flow equation of Quantum Einstein Gravity to determine the renormalization group behavior of a…

High Energy Physics - Theory · Physics 2009-11-07 M. Reuter , F. Saueressig

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

The renormalization group in effective quantum gravity can be consistently formulated using the Vilkovisky and DeWitt version of effective action and assuming a non-zero cosmological constant. Taking into account that the vacuum counterpart…

High Energy Physics - Theory · Physics 2022-11-08 Breno L. Giacchini , Tibério de Paula Netto , Ilya L. Shapiro

As is well known, the universally accepted theory as quantum gravity (QG) doesn't exist. One of the main reasons for that is that quantized general relativity is perturbatively nonrenormalizable. But there are several theories whose…

High Energy Physics - Theory · Physics 2007-05-23 T. Tsuneyama

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 study the non-perturbative renormalization group flow of f(R)-gravity in three-dimensional Asymptotically Safe Quantum Einstein Gravity. Within the conformally reduced approximation, we derive an exact partial differential equation…

High Energy Physics - Theory · Physics 2013-02-07 Maximilian Demmel , Frank Saueressig , Omar Zanusso

It is a tantalising possibility that quantum gravity (QG) states remaining coherent at astrophysical, galactic and cosmological scales could exist and that they could play a crucial role in understanding macroscopic gravitational effects.…

General Relativity and Quantum Cosmology · Physics 2020-07-01 M. Cadoni , M. Tuveri , A. P. Sanna

Asymptotic Safety provides a mechanism for constructing a consistent and predictive quantum theory of gravity valid on all length scales. Its key ingredient is a non-Gaussian fixed point of the gravitational renormalization group flow which…

High Energy Physics - Theory · Physics 2017-04-26 Jorn Biemans , Alessia Platania , Frank Saueressig

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 discuss the non-perturbative renormalization group flow of Quantum Electrodynamics (QED) coupled to Quantum Einstein Gravity (QEG) and explore the possibilities for defining its continuum limit at a fixed point that would lead to a…

High Energy Physics - Theory · Physics 2015-05-27 Ulrich Harst , Martin Reuter

Using as an example the Einstein gravity with the cosmological constant, we discuss the calculation of renormalization group functions off shell. We found, that gauge dependent terms should be absorbed by the nonlinear renormalization of…

General Relativity and Quantum Cosmology · Physics 2008-02-03 K. Kazakov , P. Pronin , K. Stepanyantz

A new exact renormalization group equation for the effective average action of Euclidean quantum gravity is constructed. It is formulated in terms of the component fields appearing in the transverse-traceless decomposition of the metric. It…

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