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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

Loop Quantum Gravity (LQG) is one of the leading approaches to unify quantum physics and General Relativity (GR). The Hilbert space of LQG is spanned by spin-networks which describe the local geometry of quantum space-time. Simulation of…

General Relativity and Quantum Cosmology · Physics 2021-12-21 Swapnil Nitin Shah

We consider $\kappa$-deformed relativistic quantum phase space and possible implementations of the Lorentz algebra. There are two ways of performing such implementations. One is a simple extension where the Poincar\'e algebra is unaltered,…

High Energy Physics - Theory · Physics 2019-06-26 D. Meljanac , S. Meljanac , S. Mignemi , R. Štrajn

The U(1)$^3$ model for 3+1 Euclidian signature general relativity is an interacting, generally covariant field theory with two physical polarisations that shares many features of Lorentzian general relativity. In particular, it displays a…

General Relativity and Quantum Cosmology · Physics 2022-07-19 T. Thiemann

The aim of this paper is to find out a correspondence between one-loop effective action $W_E$ defined by means of path integral in Euclidean gravity and the free energy $F$ obtained by summation over the modes. The analysis is given for…

High Energy Physics - Theory · Physics 2011-07-19 D. Fursaev , A. Zelnikov

Wick rotation in area tensor Regge calculus is considered. The heuristical expectation is confirmed that the Lorentzian quantum measure on a spacelike area should coincide with the Euclidean measure at the same argument. The consequence is…

General Relativity and Quantum Cosmology · Physics 2010-11-19 V. M. Khatsymovsky

The existing approaches to quantization of gravity aim at giving quantum description of 3-geometry following to the ideas of the Wheeler -- DeWitt geometrodynamics. In this description the role of gauge gravitational degrees of freedom is…

General Relativity and Quantum Cosmology · Physics 2012-05-31 T. P. Shestakova

In the path integral formulation of the reduced phase space Loop Quantum Gravity (LQG), we propose a new approach to allow the spatial cubic lattice (graph) to change dynamically in the physical time evolution. The equations of motion of…

General Relativity and Quantum Cosmology · Physics 2021-07-14 Muxin Han , Hongguang Liu

In this article, the second of three, we discuss and develop the basis of a Weyl quantisation for compact Lie groups aiming at loop quantum gravity-type models. This Weyl quantisation may serve as the main mathematical tool to implement the…

Mathematical Physics · Physics 2016-07-27 Alexander Stottmeister , Thomas Thiemann

Since there are quantization ambiguities in constructing the Hamiltonian constraint operator in isotropic loop quantum cosmology, it is crucial to check whether the key features of loop quantum cosmology are robust against the ambiguities.…

General Relativity and Quantum Cosmology · Physics 2010-04-14 Jinsong Yang , You Ding , Yongge Ma

The Wigner function plays a central role in QCD as a phase space object encoding correlations among quarks, antiquarks, and gluons, yet its interpretation remains subtle due to its quasiprobabilistic nature and possible negativity. Recent…

High Energy Physics - Phenomenology · Physics 2026-04-07 Chueng-Ryong Ji , Daniel W. Piasecki

Different versions of consistent canonical realizations of hypersurface deformations of spherically symmetric space-times have been derived in models of loop quantum gravity, modifying the classical dynamics and sometimes also the structure…

General Relativity and Quantum Cosmology · Physics 2020-02-13 Martin Bojowald , Suddhasattwa Brahma , Ding Ding , Michele Ronco

A Wick rotation in the lapse (not in time) is introduced that interpolates between Riemannian and Lorentzian metrics on real manifolds admitting a codimension-one foliation. The definition refers to a fiducial foliation but covariance under…

Mathematical Physics · Physics 2025-04-11 Rudrajit Banerjee , Max Niedermaier

The Wilson loop functionals in terms of Ashtekar's variables were the first (formal) solutions to the quantized hamiltonian constraint of canonical gravity. Here it is shown that the same functionals also solve the supergravity constraints…

General Relativity and Quantum Cosmology · Physics 2010-04-06 Hans-Juergen Matschull

This paper discusses the general structure of reflection positive Euclidean covariant distributions that can be used to construct Euclidean representations of relativistic quantum mechanical models of systems of a finite number of degrees…

High Energy Physics - Theory · Physics 2025-06-26 Gohin Shaikh Samad , W. N. Polyzou

We provide a generating functional for the gravitational field, associated to the relaxation of the primary constraints as extended to the quantum sector. This requirement of the theory, relies on the assumption that a suitable time…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Erika Cerasti , Giovanni Montani

The present paper is the companion of [1] in which we proposed a scheme that tries to derive the Quantum Field Theory (QFT) on Curved Spacetimes (CST) limit from background independent Quantum General Relativity (QGR). The constructions of…

General Relativity and Quantum Cosmology · Physics 2014-11-17 Hanno Sahlmann , Thomas Thiemann

It is well known that in order to make the path integral of general relativity converge, one has to perform the Wick rotation over the conformal factor in addition to the more familiar Wick rotation of the time axis to pass to the…

High Energy Physics - Theory · Physics 2019-10-23 Ichiro Oda

We study a non-relativistic realisation of two-dimensional de Sitter gravity both from its boundary and bulk description with the goal of learning about de Sitter space and paving the way for extending the holographic duality into a…

High Energy Physics - Theory · Physics 2026-04-15 Matthias Harksen , Diego Hidalgo , Watse Sybesma

We study two-dimensional Hamiltonians in phase space with noncommutativity both in coordinates and momenta. We consider the generator of rotations on the noncommutative plane and the Lie algebra generated by Hermitian rotationally invariant…

Mathematical Physics · Physics 2016-02-17 H. Falomir , P. A. G. Pisani , F. Vega , D. Cárcamo , F. Méndez , M. Loewe