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200 papers

We derive rigorous bounds on corrections to Einstein gravity using unitarity and analyticity of graviton scattering amplitudes. In $D\geq 4$ spacetime dimensions, these consistency conditions mandate positive coefficients for certain…

High Energy Physics - Theory · Physics 2016-04-06 Brando Bellazzini , Clifford Cheung , Grant N. Remmen

We perform a minisuperspace analysis of an information-theoretic nonlinear Wheeler-deWitt (WDW) equation for de Sitter universes. The nonlinear WDW equation, which is in the form of a difference-differential equation, is transformed into a…

General Relativity and Quantum Cosmology · Physics 2012-04-02 Rajesh R. Parwani , Siti Nursaba Tarih

The canonical approach to quantum gravity has been put on a firm mathematical foundation in the recent decades. Even the quantum dynamics can be rigorously defined, however, due to the tremendously non-polynomial character of the…

General Relativity and Quantum Cosmology · Physics 2020-03-31 Thomas Thiemann

This article shows in detail the computations made for the poster presented at the Symposium "Frontiers of Fundamental Physics" in July 2014. As was shown in a previous publication, a quantum gravity formulation exists on the basis of…

General Relativity and Quantum Cosmology · Physics 2015-01-05 Pierre-André Mandrin

In this article we examine a Hamiltonian constraint operator governing the dynamics of simple quantum states, whose graph consists of a single six-valent vertex, in quantum-reduced loop gravity. To this end, we first derive the action of…

General Relativity and Quantum Cosmology · Physics 2025-05-01 Ilkka Mäkinen

The canonical analysis and subsequent quantization of the (2+1)-dimensional action of pure gravity plus a cosmological constant term is considered, under the assumption of the existence of one spacelike Killing vector field. The proper…

General Relativity and Quantum Cosmology · Physics 2009-01-07 T. Christodoulakis , G. Doulis , Petros A Terzis , E. Melas , Th. Grammenos , G. O. Papadopoulos , A. Spanou

An alternative quantization of the gravitational Hamiltonian constraint of the $k=-1$ Friedmann-Robertson-Walker model is proposed by treating the Euclidean term and the Lorentzian term independently, mimicking the treatment of full loop…

General Relativity and Quantum Cosmology · Physics 2023-02-23 Jinsong Yang , Cong Zhang , Xiangdong Zhang

We propose an operator constraint equation for the wavefunction of the Universe that admits genuine evolution. While the corresponding classical theory is equivalent to the canonical decomposition of General Relativity, the quantum theory…

General Relativity and Quantum Cosmology · Physics 2014-04-03 Sean Gryb , Karim Thebault

We construct a state in the loop quantum gravity theory with zero cosmological constant, which should correspond to the flat spacetime vacuum solution. This is done by defining the loop transform coefficients of a flat connection…

General Relativity and Quantum Cosmology · Physics 2009-01-16 A. Mikovic

The present work deals with Einstein-aether Scalar tensor gravity in the background of homogeneous and isotropic flat FLRW space-time model. The Noether symmetry vector identifies a transformation in the augmented space so that the field…

General Relativity and Quantum Cosmology · Physics 2024-07-12 Dipanakr Laya , Roshni Bhaumik , Sourav Dutta , Subenoy Chakraborty

In contrast to previous work in the field, we construct the Loop Quantum Cosmology (LQC) of the flat isotropic model with a massless scalar field in the absence of higher order curvature corrections to the gravitational part of the…

General Relativity and Quantum Cosmology · Physics 2015-01-30 Madhavan Varadarajan

A gauge invariant mathematical formalism based on deformation quantization is outlined to model an $\mathcal{N}=2$ supersymmetric system of a spin $1/2$ charged particle placed in a nocommutative plane under the influence of a vertical…

Mathematical Physics · Physics 2024-07-02 Md. Rafsanjany Jim , S. Hasibul Hassan Chowdhury

Exploiting inherent symmetries is a common and effective approach to speed up the simulation of quantum systems. However, efficiently accounting for non-Abelian symmetries, such as the $SU(2)$ total-spin symmetry, remains a major challenge.…

Quantum Physics · Physics 2024-12-20 Anthony Gandon , Alberto Baiardi , Max Rossmannek , Werner Dobrautz , Ivano Tavernelli

A relativistic spin operator is to be the difference between the total and orbital angular momentum. As the unique position operator for a localized state, the remarkable Newton-Wigner position operator, which has all desirable commutation…

Quantum Physics · Physics 2014-12-02 Taeseung Choi

Stationary spherically symmetric gravity is equivalent to a nonlinear coset sigma model on SL(2,R)/SO(2) coupled to a gravitational remnant. Classically there are stationary solutions besides the static Schwarzschild metric labeled by the…

General Relativity and Quantum Cosmology · Physics 2009-10-28 Helia Hollmann

We present a systematic expansion of all constraint equations in canonical quantum gravity up to the order of the inverse Planck mass squared. It is demonstrated that this method generates the conventional Feynman diagrammatic technique…

General Relativity and Quantum Cosmology · Physics 2009-10-30 A. O. Barvinsky , C. Kiefer

Recently a new picture has been developed for examining Wilson lines, and the corresponding anomalous dimensions which govern their renormalization properties. By making a particular coordinate transform, the calculation of the cusp…

High Energy Physics - Theory · Physics 2012-05-29 D. J. Miller , C. D. White

We investigate the asymptotic dynamics of quantum networks under repeated applications of random unitary operations. It is shown that in the asymptotic limit of large numbers of iterations this dynamics is generally governed by a typically…

Quantum Physics · Physics 2009-04-02 J. Novotny , G. Alber , I. Jex

Barrett and Crane have proposed a model of simplicial Euclidean quantum gravity in which a central role is played by a class of Spin(4) spin networks called "relativistic spin networks" which satisfy a series of physically motivated…

General Relativity and Quantum Cosmology · Physics 2015-06-25 Michael P. Reisenberger

The article surveys quantization schemes for metric graphs with spin. Typically quantum graphs are defined with the Laplace or Schrodinger operator which describe particles whose intrinsic angular momentum (spin) is zero. However, in many…

Mathematical Physics · Physics 2010-12-06 J. M. Harrison