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We explore and discuss corrections to the Newton potential from the quantum effects of conformal matter fields. In this special case, one can compare different approaches, including that of effective quantum gravity and another, based on…

High Energy Physics - Theory · Physics 2026-05-08 Riccardo Fecchio , Ilya L. Shapiro

We discuss the effective potential of the conformal factor in the effective average action approach to Quantum Einstein Gravity. Without invoking any truncation or other approximations we show that if the theory has has a non-Gaussian…

High Energy Physics - Theory · Physics 2010-11-11 Jan-Eric Daum , Martin Reuter

Following the same steps made for a scalar field in a parallel publication, we propose a class of perturbative theories of quantum gravity based on fractional operators, where the kinetic operator of the graviton is either made of…

General Relativity and Quantum Cosmology · Physics 2021-08-16 Gianluca Calcagni

We show that under certain technical assumptions, including the existence of a constant mean curvature (CMC) slice and strict positivity of the scalar field, general relativity conformally coupled to a scalar field can be quantised on a…

General Relativity and Quantum Cosmology · Physics 2013-04-25 Norbert Bodendorfer , Alexander Stottmeister , Andreas Thurn

The phase diagram of 2d Lorentzian quantum gravity (LQG) coupled to conformal matter is studied. A phase transition is observed at $c=c_{\rm crit}$ ($1/2<c_{\rm crit}<4$) which can be thought of as the analogue of the $c=1$ barrier of…

High Energy Physics - Lattice · Physics 2015-06-25 Jan Ambjorn , K. N. Anagnostopoulos , R. Loll

This introductory review is addressed to beginning researchers. Some of the distinguishing features of loop quantum gravity are illustrated through loop quantum cosmology of FRW models. In particular, these examples illustrate: i) how…

General Relativity and Quantum Cosmology · Physics 2010-11-11 Abhay Ashtekar

Formulating a quantum theory of gravity lies at the heart of fundamental theoretical physics. This collection of lecture notes encompasses a selection of topics that were covered in six mini-courses at the Nordita PhD school "Towards…

High Energy Physics - Theory · Physics 2025-10-10 Ivano Basile , Luca Buoninfante , Francesco Di Filippo , Benjamin Knorr , Alessia Platania , Anna Tokareva

Paying attention to conformal invariance as the invariance under local transformations of units of measure, we take a conformal invariant quantum field as a quantum matter theory in which one has the freedom to choose the values of units of…

General Relativity and Quantum Cosmology · Physics 2017-05-17 Nadereh Namavarian

After establishing the positivity constraint and spin content of the theory for gravitons interacting with a necessarily, and \textit{a priori}, \textit{non}-conserved external energy-momentum tensor, the expectation value formalism of the…

High Energy Physics - Theory · Physics 2013-11-12 E. B. Manoukian , S. Sukkhasena

We discuss the influence of gravitational effects on the stabilization of the chromomagnetic vacuum. The one-loop effective potential for a covariantly constant SU(2) gauge field in ${\bf S}^2 \times {\bf R}^2$ and ${\bf T}^2 \times {\bf…

High Energy Physics - Theory · Physics 2009-09-17 Emilio Elizalde , Sergei D. Odintsov , August Romeo

A sketch of a recent approach to quantum gravity is presented which involves several unconventional aspects. The basic ingredients include: (1) Affine kinematical variables; (2) Affine coherent states; (3) Projection operator approach for…

General Relativity and Quantum Cosmology · Physics 2017-08-23 John R. Klauder

We consider the most general action for gravity which is quadratic in curvature. In this case first order and second order formalisms are not equivalent. This framework is a good candidate for a unitary and renormalizable theory of the…

High Energy Physics - Theory · Physics 2017-12-22 Enrique Alvarez , Jesus Anero , Sergio Gonzalez-Martin

A summary of recent work related to the calculation of loop quantum gravity induced corrections to standard particle (photons and spin 1/2 fermions) dynamics in flat space is presented. Stringent bounds upon the parameters characterizing…

High Energy Physics - Phenomenology · Physics 2017-08-23 Luis F. Urrutia

The macroscopic effects of the quantum conformal anomaly are evaluated in a simplified two-dimensional model of gravitational collapse. The effective action and stress tensor of the anomaly can be expressed in a local quadratic form by the…

General Relativity and Quantum Cosmology · Physics 2023-09-08 Emil Mottola , Mani Chandra , Gian Mario Manca , Evgeny Sorkin

Most of the potential physical effects of loop quantum gravity have been derived in effective models that modify the constraints of canonical general relativity in specific forms. Emergent modified gravity evaluates important conditions…

General Relativity and Quantum Cosmology · Physics 2025-05-01 Idrus Husin Belfaqih , Martin Bojowald , Suddhasattwa Brahma , Erick I. Duque

In this paper we consider a static and regular fluid generating a locally spherically symmetric and time-independent space-time and calculate the leading quantum corrections to the metric to first order in curvature. Starting from a…

High Energy Physics - Theory · Physics 2020-07-13 Xavier Calmet , Roberto Casadio , Folkert Kuipers

A fundamental problem with attempting to quantize general relativity is its perturbative non-renormalizability. However, this fact does not rule out the possibility that non-perturbative effects can be computed, at least in some…

General Relativity and Quantum Cosmology · Physics 2016-08-31 Viqar Husain , Sebastian Jaimungal

The effects of different forms of weak measurements on the nature of the measurement induced phase transition are theoretically studied in hybrid random quantum circuits of qubits. We use a combination of entanglement measures, ancilla…

Quantum Physics · Physics 2024-12-10 Kemal Aziz , Ahana Chakraborty , J. H. Pixley

We show how to simulate U(1) gauge fields coupled to three-dimensional quantum gravity and then examine the phase diagram of this system. Quenched mean field theory suggests that a transition separates confined and deconfined phases (for…

High Energy Physics - Lattice · Physics 2009-10-22 Ray L. Renken , Simon M. Catterall , John B. Kogut

The new information-theoretic Process Physics has shown that space is a quantum foam system with gravity being, in effect, an inhomogeneous in-flow of the quantum foam into matter. The theory predicts that absolute motion with respect to…

General Physics · Physics 2010-07-14 Reginald T. Cahill