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We study spherically symmetric configurations of the quadratic $f(R)$ gravity in the Einstein frame. In case of a purely gravitational system, we have determined the global qualitative behavior of the metric and the scalaron field for all…

General Relativity and Quantum Cosmology · Physics 2024-07-30 V. I. Zhdanov , O. S. Stashko , Yu. V. Shtanov

In this thesis we investigate various fundamental aspects of asymptotically safe quantum gravity, in particular the compatibility of Asymptotic Safety with the requirements for background independence and unitarity. The first part contains…

High Energy Physics - Theory · Physics 2017-01-31 Andreas Nink

The existence of a simple spherically symmetric and static solution of the Einstein equations in the presence of a cosmological constant vanishing outside a definite value of the radial distance is investigated. A particular succession of…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Alejandro Cabo , Alejandro Garcia-Chung , Alejandro Rosabal

We extend the work in our earlier article [4] to show that time-periodic, asymptotically-flat solutions of the Einstein equations analytic at scri, whose source is one of a range of scalar-field models, are necessarily stationary. We also…

General Relativity and Quantum Cosmology · Physics 2011-01-18 Jiří Bičák , Martin Scholtz , Paul Tod

Asymptotic safety generalizes asymptotic freedom and could contribute to understanding physics beyond the Standard Model. It is a candidate scenario to provide an ultraviolet extension for the effective quantum field theory of gravity…

High Energy Physics - Theory · Physics 2019-02-22 Astrid Eichhorn

We consider general relativity with cosmological constant minimally coupled to electromagnetic field and assume that four-dimensional space-time manifold is the warped product of two surfaces with Lorentzian and Euclidean signature metrics.…

General Physics · Physics 2019-07-31 D. E. Afanasev , M. O. Katanaev

The time independent spherically symmetric solutions of General Relativity (GR) coupled to a dynamical unit timelike vector are studied. We find there is a three-parameter family of solutions with this symmetry. Imposing asymptotic flatness…

General Relativity and Quantum Cosmology · Physics 2010-02-05 Christopher Eling , Ted Jacobson

We investigate the asymptotic safety conjecture for quantum gravity including curvature invariants beyond Ricci scalars. Our strategy is put to work for families of gravitational actions which depend on functions of the Ricci scalar, the…

High Energy Physics - Theory · Physics 2018-04-18 Kevin G. Falls , Callum R. King , Daniel F. Litim , Kostas Nikolakopoulos , Christoph Rahmede

We investigate the future asymptotics of spatially homogeneous space-times with a positive cosmological constant by using and further developing geometric conformal methods in General Relativity. For a large class of source fields,…

General Relativity and Quantum Cosmology · Physics 2023-02-06 Christian Lübbe , Filipe C. Mena

We continue our work on the study of spherically symmetric loop quantum gravity coupled to two spherically symmetric scalar fields, one that acts as a clock. As a consequence of the presence of the latter, we can define a true Hamiltonian…

General Relativity and Quantum Cosmology · Physics 2024-02-07 Rodolfo Gambini , Jorge Pullin

Exact solutions of the Einstein's field equations describing a spherically symmetric cosmological model without a big bang or any other kind of singularity recently obtained by Dadhich and Patel (2000) are revisited. The matter content of…

General Relativity and Quantum Cosmology · Physics 2010-11-19 Anirudh Pradhan , Kashika Srivastava , Amrit Lal Ahuja

We adopt an effective action inspired by asymptotically safe gravity, in which the effective gravitational constant is parametrized as $G(\epsilon) = G_{N} /[1 + \tilde{\omega} (G_{N}^{2} \epsilon)^{\alpha}]$, where $G_{N}$ and $\epsilon$…

General Relativity and Quantum Cosmology · Physics 2025-06-18 Tomohiro Harada , Chiang-Mei Chen , Rituparna Mandal

We study the non-perturbative renormalisation of quantum gravity in four dimensions. Taking care to disentangle physical degrees of freedom, we observe the topological nature of conformal fluctuations arising from the functional measure.…

High Energy Physics - Theory · Physics 2016-04-27 Kevin Falls

We explore whether quantum gravity effects within the asymptotic safety paradigm can provide a predictive ultraviolet completion for Abelian gauge theories. We evaluate the effect of quantum gravity fluctuations on the running couplings in…

High Energy Physics - Theory · Physics 2017-05-18 Nicolai Christiansen , Astrid Eichhorn

Asymptotically safe quantum gravity is an approach to quantum gravity that achieves formulates a standard quantum field theory for the metric. Therefore, even the deep quantum gravity regime, that is expected to determine the true structure…

General Relativity and Quantum Cosmology · Physics 2022-12-20 Astrid Eichhorn , Aaron Held

We provide a conceptual assessment of some aspects of fundamental quantum field theories of gravity in light of foundational aspects of the swampland program. On the one hand, asymptotically safe quantum gravity may provide a simple and…

High Energy Physics - Theory · Physics 2026-02-04 Ivano Basile , Benjamin Knorr , Alessia Platania , Marc Schiffer

We introduce a two-parameter static, nonspherically-symmetric black hole solution in the Einstein theory of gravity coupled with a massless scalar field. The scalar field depends only on the polar coordinate $\theta$ in the spherical…

General Relativity and Quantum Cosmology · Physics 2025-02-21 S. Habib Mazharimousavi

We discuss the linearization of Einstein equations in the presence of a cosmological constant, by expanding the solution for the metric around a flat Minkowski space-time. We demonstrate that one can find consistent solutions to the…

General Relativity and Quantum Cosmology · Physics 2010-04-14 Jose Bernabeu , Catalina Espinoza , Nick E. Mavromatos

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

Recent works by the second author and Maxwell et al. have shown that the Einstein-scalar field conformal constraint equations are highly complex and generally intractable, even in the vacuum case. In this article, to gain a clearer…

General Relativity and Quantum Cosmology · Physics 2026-03-11 Philippe Castillon , Cang Nguyen-The