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Loop quantum gravity in its Hamiltonian form relies on a connection formulation of the gravitational phase space with three key properties: 1.) a compact gauge group, 2.) real variables, and 3.) canonical Poisson brackets. In conjunction,…

General Relativity and Quantum Cosmology · Physics 2024-12-09 Norbert Bodendorfer , Konstantin Eder , Xiangdong Zhang

Recently, there were works claiming that path integral quantisation of gauge theories necessarily requires relaxation of Lagrangian constraints. As has also been noted in the literature, it is of course wrong since there perfectly exist…

High Energy Physics - Theory · Physics 2026-03-12 Alexey Golovnev , Kirill Russkov

This article presents an "in-a-nutshell" yet self-contained introductory review on loop quantum gravity (LQG) -- a background-independent, nonperturbative approach to a consistent quantum theory of gravity. Instead of rigorous and…

General Relativity and Quantum Cosmology · Physics 2014-12-30 Dah-Wei Chiou

Using the Ashtekar formulation, it is shown that the G_{Newton} --> 0 limit of Euclidean or complexified general relativity is not a free field theory, but is a theory that describes a linearized self-dual connection propagating on an…

High Energy Physics - Theory · Physics 2010-04-06 Lee Smolin

We discuss the most general effective Lagrangian obtained from the assumption that the degrees of freedom to be quantized, in a black hole, are on the horizon. The effective Lagrangian depends only on the induced metric and the extrinsic…

General Relativity and Quantum Cosmology · Physics 2010-11-01 A. Buonanno , M. Gattobigio , M. Maggiore , L. Pilo , C. Ungarelli

Despite the importance of the path integral, there have been relatively few attempts to look to the Lagrangian for a more realistic framework that might underlie quantum theory. While such realism is not available for the standard path…

Quantum Physics · Physics 2013-01-30 K. B. Wharton

Algebraically speaking, linear time-invariant (LTI) systems can be considered as modules. In this framework, controllability is translated as the freeness of the system module. Optimal control mainly relies on quadratic Lagrangians and the…

Optimization and Control · Mathematics 2024-10-10 Cédric Join , Emmanuel Delaleau , Michel Fliess

One of several possibilities to construct a quantum theory of gravity is employing the Feynman path integral. This approach is plagued by some problems: the integration measure is not uniquely defined, the Einstein-Hilbert action unbounded,…

High Energy Physics - Lattice · Physics 2008-02-03 J. Riedler

Efficient control of qubits plays a key role in quantum information processing. In the current work, an alternative set of differential equations are derived for an optimal quantum control of single or multiple qubits with or without…

Quantum Physics · Physics 2020-11-26 Ding Wang , Haowei Shi , Yueheng Lan

The first law of black hole mechanics (in the form derived by Wald), is expressed in terms of integrals over surfaces, at the horizon and spatial infinity, of a stationary, axisymmetric black hole, in a diffeomorphism invariant Lagrangian…

General Relativity and Quantum Cosmology · Physics 2009-10-28 Vivek Iyer

We provide a new paradigm for quantum simulation that is based on path integration that allows quantum speedups to be observed for problems that are more naturally expressed using the path integral formalism rather than the conventional…

Quantum Physics · Physics 2024-10-15 Serene Shum , Nathan Wiebe

We present an effective theory to describe the quantization of spherically symmetric vacuum in loop quantum gravity. We include anomaly-free holonomy corrections through a canonical transformation of the Hamiltonian of general relativity,…

General Relativity and Quantum Cosmology · Physics 2023-04-18 Asier Alonso-Bardaji , David Brizuela , Raül Vera

The Hamiltonian formulation of scalar-tensor theories of gravity is derived from their Lagrangian formulation by Hamiltonian analysis. The Hamiltonian formalism marks off two sectors of the theories by the coupling parameter $\omega(\phi)$.…

General Relativity and Quantum Cosmology · Physics 2015-05-28 Xiangdong Zhang , Yongge Ma

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 explore the Lagrangian equation in the background of generalized uncertainty principle. The tunneling radiation through the black ring horizon is observed. We investigated the tunneling radiation through the Hamilton-Jacobi method for…

General Relativity and Quantum Cosmology · Physics 2021-01-20 Riasat Ali , Kazuharu Bamba , Muhammad Asgher , Syed Asif Ali Shah

Imaginary time is often used in quantum tunnelling calculations. This article advocates a conceptually sounder alternative: complex lapse. In the ``3+1'' action for the Einstein gravitational field minimally coupled to a Klein-Gordon field,…

General Relativity and Quantum Cosmology · Physics 2009-10-28 Sean A. Hayward

We show that the Einstein-Hilbert action for the gravitational field can be obtained as a linear low-energy approximation for the dynamical massless fields in the theory with the lagrangian quadratic in the gauge field strength-tensor of…

High Energy Physics - Phenomenology · Physics 2007-05-23 V. V. Kiselev

The basic features of a quantum field theory which is Poincar\'e invariant, gauge invariant, finite and unitary to all orders of perturbation theory are reviewed. Quantum gravity is finite and unitary to all orders of perturbation theory.…

High Energy Physics - Theory · Physics 2007-05-23 J. W. Moffat

We develop the gauge approach based on the Lorentz group to the gravity with torsion. With a Lagrangian quadratic in curvature we show that the Einstein-Hilbert action can be induced from a simple gauge model due to quantum corrections of…

General Relativity and Quantum Cosmology · Physics 2007-05-23 S. W. Kim , D. G. Pak

We obtain rotating black hole metric for higher dimensional Einstein and pure Lovelock gravity by employing two independent and well motivated methods. One is based on the principle of incorporation of Newtonian acceleration for timelike…

General Relativity and Quantum Cosmology · Physics 2013-09-27 Naresh Dadhich , Sushant G. Ghosh