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We present new second derivative, generally covariant theories of gravity for spherically symmetric spacetimes (general covariance is in the $t-r$ plane) belonging to the class where the spherically symmetric Einstein-Hilbert theory is…

General Relativity and Quantum Cosmology · Physics 2015-05-20 Rakesh Tibrewala

Deformed special relativity is embedded in deformed general relativity using the methods of canonical relativity and loop quantum gravity. Phase-space dependent deformations of symmetry algebras then appear, which in some regimes can be…

General Relativity and Quantum Cosmology · Physics 2013-08-05 Martin Bojowald , George M. Paily

We revisit the non-singular black hole solution in (extended) mimetic gravity with a limiting curvature from a Hamiltonian point of view. We introduce a parameterization of the phase space which allows us to describe fully the Hamiltonian…

General Relativity and Quantum Cosmology · Physics 2018-06-13 Jibril Ben Achour , Frederic Lamy , Hongguang Liu , Karim Noui

Certain versions of mimetic gravity have recently been claimed to present potential covariant theories of canonically modified spherically symmetric gravity, motivated by ingredients from loop quantum gravity. If such an equivalence were to…

General Relativity and Quantum Cosmology · Physics 2024-04-22 Martin Bojowald , Erick I. Duque

We present for the first time an explicit exposition of quantum corrections within the cubic Galileon theory including the effect of quantum gravity, in a background- and gauge-invariant manner, employing the field-reparametrisation…

High Energy Physics - Theory · Physics 2017-05-17 Ippocratis D. Saltas , Vincenzo Vitagliano

Although the cosmological perturbations with inverse-volume corrections from loop quantum cosmology have been studied using the anomaly-free algebra approach in much of the literature, there still remains an important issue that some…

General Relativity and Quantum Cosmology · Physics 2018-10-18 Yu Han

This article provides a cartoon of the quantization of General Relativity using the ideas of effective field theory. These ideas underpin the use of General Relativity as a theory from which precise predictions are possible, since they show…

General Relativity and Quantum Cosmology · Physics 2007-05-23 C. P. Burgess

Vielbeins are necessary when coupling General Relativity (GR) to fermionic matter. This enhances the gauge group of GR to include local Lorentz transformations. In view of a reduced phase space formulation of quantum gravity, in this work…

General Relativity and Quantum Cosmology · Physics 2023-05-12 Thomas Thiemann

The cosmological tensor perturbation equation with generalized holonomy corrections is derived in the framework of effective loop quantum gravity. This results in a generalized dispersion relation for gravitational waves, encompassing…

General Relativity and Quantum Cosmology · Physics 2024-08-13 Shulan Li , Jian-Pin Wu

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

In this paper, we are going to discuss the gauge reduction with respect to the simplicity constraint in both classical and quantum theory of all dimensional loop quantum gravity. With the gauge reduction with respect to edge-simplicity…

General Relativity and Quantum Cosmology · Physics 2023-03-08 Gaoping Long , Xiangdong Zhang

Canonical quantization of spherically symmetric space-times is carried out, using real-valued densitized triads and extrinsic curvature components, with specific factor ordering choices ensuring in an anomaly free quantum constraint…

General Relativity and Quantum Cosmology · Physics 2015-06-05 Suddhasattwa Brahma

We develop an effective framework for the $\bar\mu$ scheme of holonomy corrections motivated by loop quantum gravity for vacuum spherically symmetric space-times. This is done by imposing the areal gauge in the classical theory, and then…

General Relativity and Quantum Cosmology · Physics 2022-06-15 Jarod George Kelly , Robert Santacruz , Edward Wilson-Ewing

Scalar cosmological perturbations in loop quantum cosmology (LQC) is revisited in a covariant manner, using self dual Ashtekar variables. For real-valued Ashtekar-Barbero variables, this `deformed algebra' approach has been shown to…

General Relativity and Quantum Cosmology · Physics 2016-10-25 Jibril Ben Achour , Suddhasattwa Brahma , Julien Grain , Antonino Marciano

In [1] we initiated an approach towards quantizing the Hamiltonian constraint in Loop Quantum Gravity (LQG) by requiring that it generates an anomaly-free representation of constraint algebra off-shell. We investigated this issue in the…

General Relativity and Quantum Cosmology · Physics 2014-11-13 Adam Henderson , Alok Laddha , casey Tomlin

We present a covariant model of a spherically symmetric black hole with corrections motivated by loop quantum gravity. The effective modifications, parametrized by a positive constant $\lambda$, are implemented through a canonical…

General Relativity and Quantum Cosmology · Physics 2022-10-07 Asier Alonso-Bardaji , David Brizuela , Raül Vera

We develop a quantum effective action for scalar-tensor theories of gravity which is both spacetime diffeomorphism invariant and field reparameterisation (frame) invariant beyond the classical approximation. We achieve this by extending the…

High Energy Physics - Theory · Physics 2020-08-26 Kieran Finn , Sotirios Karamitsos , Apostolos Pilaftsis

The covariance of loop quantum gravity studies of spherically symmetric space-times has recently been questioned. This is a reasonable worry, given that they are formulated in terms of slicing-dependent variables. We show explicitly that…

General Relativity and Quantum Cosmology · Physics 2022-02-21 Rodolfo Gambini , Javier Olmedo , Jorge Pullin

Effective equations are often useful to extract physical information from quantum theories without having to face all technical and conceptual difficulties. One can then describe aspects of the quantum system by equations of classical type,…

High Energy Physics - Theory · Physics 2008-11-26 Martin Bojowald , Aureliano Skirzewski

It is shown that introducing the quantum effects using deBroglie--Bohm theory in the canonical formulation of gravity would change the constraints algebra. The new algebra is derived and shown that it is the clear projection of general…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Ali Shojai , Fatimah Shojai