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We study a series of the Wess-Zumino actions obtained by repeatedly integrating conformal anomalies with respect to the conformal-factor field that appear at higher loops. We show that they arise as physical quantities required to make…

High Energy Physics - Theory · Physics 2020-12-30 Ken-ji Hamada

An heuristic semiclassical procedure that incorporates quantum gravity induced corrections in the description of photons and spin 1/2 fermions is reviewed. Such modifications are calculated in the framework of loop quantum gravity and they…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Luis Urrutia

We calculate the quantum corrections to the gauge-invariant gravitational potentials of spinning particles in flat space, induced by loops of both massive and massless matter fields of various types. While the corrections to the Newtonian…

High Energy Physics - Theory · Physics 2016-12-13 Markus B. Fröb

We discuss two distinct realizations of the diffeomorphism group for metric gravity, which give rise to theories that are classically equivalent, but quantum mechanically distinct. We renormalize them in $d=2+\epsilon$ dimensions,…

High Energy Physics - Theory · Physics 2021-11-03 Riccardo Martini , Alessandro Ugolotti , Francesco Del Porro , Omar Zanusso

We study the quantization of spherically symmetric vacuum spacetimes within loop quantum gravity. In particular, we give additional details about our previous work in which we showed that one could complete the quantization the model and…

General Relativity and Quantum Cosmology · Physics 2016-12-20 Rodolfo Gambini , Javier Olmedo , Jorge Pullin

A fully consistent linear perturbation theory for cosmology is derived in the presence of quantum corrections as they are suggested by properties of inverse volume operators in loop quantum gravity. The underlying constraints present a…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Martin Bojowald , Golam Mortuza Hossain , Mikhail Kagan , S. Shankaranarayanan

Loop quantum gravity corrections, in the presence of inhomogeneities, can lead to a deformed constraint algebra. Such a deformation implies that the effective theory is no longer generally covariant. As a consequence, the geometrical…

General Relativity and Quantum Cosmology · Physics 2015-06-17 Rakesh Tibrewala

We investigate a possible unified theory of all interactions which is based only on fundamental spinor fields. The vielbein and metric arise as composite objects. The effective quantum gravitational theory can lead to a modification of…

High Energy Physics - Theory · Physics 2009-11-10 C. Wetterich

We investigate up to which extend the kinematic setting of loop quantum gravity can be fit into a diffeomorphism invariant setting of algebraic QFT generalizing the Haag-Kastler setting of Wightman type QFT. The net of local (Weyl-)algebras…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Martin Rainer

We reexamine the large quantum gravity effects discovered by Ashtekar in the context of 2+1 dimensional gravity coupled to matter. We study an alternative one-parameter family of coherent states of the theory in which the large quantum…

General Relativity and Quantum Cosmology · Physics 2009-10-30 Rodolfo Gambini , Jorge Pullin

A new framework of loop quantization that assimilates conformal and scale invariance is constructed and is found to be applicable to a large class of physically important theories of gravity and gravity-matter systems. They include general…

General Relativity and Quantum Cosmology · Physics 2019-01-02 Charles H. -T. Wang , Daniel P. F. Rodrigues

We discuss effects of loss of coherence in low energy quantum systems caused by or related to gravitation, referred to as gravitational decoherence. These effects, resulting from random metric fluctuations, for instance, promise to be…

Quantum Physics · Physics 2017-09-26 Angelo Bassi , André Großardt , Hendrik Ulbricht

We discuss the fate of diffeomorphism symmetry in discrete gravity. Diffeomorphism symmetry is typically broken by the discretization. This has repercussions for the observable content and the canonical formulation of the theory. It might…

General Relativity and Quantum Cosmology · Physics 2015-05-14 B. Bahr , B. Dittrich

We derive the one-loop partition function for three-dimensional quantum gravity in a finite-radius thermal twisted flat space with a conical defect, reproducing the massive BMS$_3$ character. We perform the computation in both discrete and…

General Relativity and Quantum Cosmology · Physics 2025-06-06 T. Mursheed Amith , Alicia Castro

Recently\cite{BQG}, it was shown that quantum effects of matter could be identified with the conformal degree of freedom of the space-time metric. Accordingly, one can introduce quantum effects either by making a scale transformation (i.e.…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Fatimah Shojai , Ali Shojai , Mehdi Golshani

A simple model is constructed which allows to compute modified dispersion relations with effects from loop quantum gravity. Different quantization choices can be realized and their effects on the order of corrections studied explicitly. A…

General Relativity and Quantum Cosmology · Physics 2016-08-31 Martin Bojowald , Hugo A. Morales-Tecotl , Hanno Sahlmann

We expect quantum field theories for matter to acquire intricate corrections due to their coupling to quantum fluctuations of the gravitational field. This can be precisely worked out in 3d quantum gravity: after integrating out quantum…

High Energy Physics - Theory · Physics 2024-06-06 Etera R. Livine , Valentine Maris

As a canonical and generally covariant gauge theory, loop quantum gravity requires special techniques to derive effective actions or equations. If the proper constructions are taken into account, the theory, in spite of considerable…

General Relativity and Quantum Cosmology · Physics 2013-08-02 Martin Bojowald

A model is proposed to demonstrate that classical general relativity can emerge from loop quantum gravity, in a relational description of gravitational field in terms of the coordinates given by matter. Local Dirac observables and coherent…

General Relativity and Quantum Cosmology · Physics 2015-06-03 Chun-Yen Lin

We investigate the action of diffeomorphisms in the context of Hamiltonian Gravity. By considering how the diffeomorphism-invariant Hilbert space of Loop Quantum Gravity should be constructed, we formulate a physical principle by demanding,…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Tim Koslowski