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We clearly formulate and study further a conjecture of effective field theory interaction with gravity in the cosmological context. The conjecture stems from the fact that the melding of quantum theory and gravity typically indicates the…

High Energy Physics - Theory · Physics 2008-10-15 Michael Maziashvili

No theory of four-dimensional quantum gravity exists as yet. In this situation the two-dimensional theory, which can be analyzed by conventional field-theoretical methods, can serve as a toy model for studying some aspects of quantum…

High Energy Physics - Theory · Physics 2015-06-26 J. Ambjorn , J. L. Nielsen , J. Rolf , R. Loll

The current understanding of renormalization in quantum gravity (QG) is based on the fact that UV divergences of effective actions in the covariant QG models are covariant local expressions. This fundamental statement plays a central role…

High Energy Physics - Theory · Physics 2024-07-30 P. M. Lavrov , I. L. Shapiro

This study investigates the quantumness of gravity under the setup of the atomic interferometry from the viewpoint of mass-energy equivalence. We evaluated interference visibility considering a particle with internal energy levels in a…

General Relativity and Quantum Cosmology · Physics 2022-12-16 Youka Kaku , Shin'ya Maeda , Yasusada Nambu , Yuki Osawa

We formulate a renormalizable quantum gravity in $2+\epsilon$ dimensions by generalizing the nonlinear sigma model approach to string theory. We find that the theory possesses the ultraviolet stable fixed point if the central charge of the…

High Energy Physics - Theory · Physics 2009-10-22 Hikaru Kawai , Yoshihisa Kitazawa , Masao Ninomiya

Matter-quantum gravity interactions can be used for direct and also indirect experimental tests of quantum gravity. We focus on photon-photon scattering in asymptotically safe gravity as a direct test of the small-scale structure of…

High Energy Physics - Theory · Physics 2012-10-05 Astrid Eichhorn

We explore the infrared limit of quantum gravity in presence of a cosmological constant or effective potential for scalar fields. For a positive effective scalar potential, one-loop perturbation theory around flat space is divergent due to…

General Relativity and Quantum Cosmology · Physics 2018-08-01 C. Wetterich

We study renormalization group equations of quantum gravity in four dimensions. We find an ultraviolet fixed point in accordance with the asymptotic safety conjecture, and infrared fixed points corresponding to general relativity with…

High Energy Physics - Theory · Physics 2012-05-22 Daniel Litim , Alejandro Satz

We provide a brief overview of what is known about Quadratic Gravity, which includes terms quadratic in the curvatures in the fundamental action. This is proposed as a renormalizeable UV completion for quantum gravity which continues to use…

High Energy Physics - Theory · Physics 2021-12-06 John F. Donoghue , Gabriel Menezes

We study the boundary terms of the spectral action of the noncommutative space, defined by the spectral triple dictated by the physical spectrum of the standard model, unifying gravity with all other fundamental interactions. We prove that…

High Energy Physics - Theory · Physics 2008-11-26 Ali H. Chamseddine , Alain Connes

A theory of quantum gravity has been recently proposed by means of a novel quantization prescription, which is able to turn the poles of the free propagators that are due to the higher derivatives into fakeons. The classical Lagrangian…

High Energy Physics - Theory · Physics 2018-05-09 Damiano Anselmi , Marco Piva

The infrared structure of quantum gravity is explored by solving a lattice version of the Wheeler-DeWitt equations. In the present paper only the case of 2+1 dimensions is considered. The nature of the wavefunction solutions is such that a…

High Energy Physics - Theory · Physics 2013-05-13 Herbert W. Hamber , Reiko Toriumi , Ruth M. Williams

Quantum renormalization group scheme provides a microscopic understanding of holography through a general mapping between the beta functions of underlying quantum field theories and the holographic actions in the bulk. We show that the…

High Energy Physics - Theory · Physics 2014-01-22 Sung-Sik Lee

Very high-energy astrophysical gamma rays suffer a suppression of their flux along their propagation due to their interaction, through the $\gamma\gamma\to e^+e^-$ pair-production process, with the soft photon backgrounds present in the…

High Energy Physics - Phenomenology · Physics 2024-10-03 J. M. Carmona , J. L. Cortés , F. Rescic , M. A. Reyes , T. Terzić , F. I. Vrban

We study UV-finite theory of induced gravity. We use scalar fields, Dirac fields and vector fields as matter fields whose one-loop effects induce the gravitational action. To obtain the mass spectrum which satisfies the UV-finiteness…

General Relativity and Quantum Cosmology · Physics 2012-09-07 Nahomi Kan , Koichiro Kobayashi , Kiyoshi Shiraishi

We discover that chiral symmetry does not act as an infrared attractor of the renormalization group flow under the impact of quantum gravity fluctuations. Thus, observationally viable quantum gravity models must respect chiral symmetry. In…

General Relativity and Quantum Cosmology · Physics 2017-02-08 Astrid Eichhorn , Stefan Lippoldt

The Wilsonian renormalization group (RG) properties of the conformal factor of the metric are profoundly altered by the fact that it has a wrong-sign kinetic term. The result is a novel perturbative continuum limit for quantum gravity,…

High Energy Physics - Theory · Physics 2020-07-15 Alex Mitchell , Tim R. Morris

We study the gravitational action induced by coupling two-dimensional non-conformal, massive matter to gravity on a compact Riemann surface. We express this gravitational action in terms of finite and well-defined quantities for any value…

High Energy Physics - Theory · Physics 2017-03-08 Adel Bilal , Laetitia Leduc

In three spacetime dimensions, where no graviton propagates, pure gravity is known to be finite. It is natural to inquire whether finiteness survives the coupling with matter. Standard arguments ensure that there exists a subtraction scheme…

High Energy Physics - Theory · Physics 2009-11-10 Damiano Anselmi

We investigate the interplay between gravity and the quantum coherence present in the state of a pulse of light propagating in curved spacetime. We first introduce an operational way to distinguish between the overall shift in the pulse…

Quantum Physics · Physics 2022-05-18 David Edward Bruschi , Symeon Chatzinotas , Frank K. Wilhelm , Andreas W. Schell