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We explore the extension of quantum cosmology outside the homogeneous approximation, using the formalism of loop quantum gravity. We introduce a model where some of the inhomogeneous degrees of freedom are present, providing a tool for…

General Relativity and Quantum Cosmology · Physics 2008-12-18 Carlo Rovelli , Francesca Vidotto

We compute second-order quantum corrections, as quantum dispersions and correlations, to a cosmological model coupling a single scalar perturbation mode to a bouncing background within Loop Quantum Cosmology (LQC). Using an effective…

General Relativity and Quantum Cosmology · Physics 2026-05-19 Héctor Hernández Hernández , Hugo Morales Técotl , Gustavo Sánchez Herrera

The quantization of the Hamiltonian for a scalar field is performed in the framework of Quantum Reduced Loop Gravity. We outline how the regularization can be performed by using the analogous tools adopted in full Loop Quantum Gravity and…

General Relativity and Quantum Cosmology · Physics 2015-12-23 Jakub Bilski , Emanuele Alesci , Francesco Cianfrani

We generalize the de Broglie-Bohm (dBB) formulation of quantum mechanics to the case of quantum gravity (QG) by using the effective action for a QG theory. This is done by replacing the dBB equations of motion with the effective action…

General Relativity and Quantum Cosmology · Physics 2025-08-05 Aleksandar Mikovic

We extend previous work concerning rest-frame partial-wave mixing in Hamiltonian effective field theory to both elongated and moving systems, where two particles are in a periodic elongated cube or have nonzero total momentum, respectively.…

High Energy Physics - Lattice · Physics 2021-05-26 Yan Li , Jia-jun Wu , Derek B. Leinweber , Anthony W. Thomas

Introducing a new method, we demonstrate how the action of reduced operators can be derived without resorting to a recoupling theory and how they exactly reproduce the results obtained in the standard approach of Quantum Reduced Loop…

General Relativity and Quantum Cosmology · Physics 2020-07-07 Jakub Bilski , Antonino Marciano

Cosmological perturbation equations are derived systematically in a canonical scheme based on Ashtekar variables. A comparison with the covariant derivation and various subtleties in the calculation and choice of gauges are pointed out.…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Martin Bojowald , Hector H. Hernández , Mikhail Kagan , Parampreet Singh , Aureliano Skirzewski

A precise interpretation of the Universe wave function is forbidden in the spirit of the Copenhagen School since a precise notion of measure operation cannot be satisfactorily defined. Here we propose a Bohmian interpretation of the…

General Relativity and Quantum Cosmology · Physics 2024-07-04 Giulia Maniccia , Giovanni Montani

Starting from an heuristic approach to the semiclassical limit in loop quantum gravity, the construction of effective Hamiltonians describing Planck length corrections to the propagation of photons and spin 1/2 fermions, leading to modified…

High Energy Physics - Phenomenology · Physics 2016-11-09 Luis F. Urrutia

Principles of successful Hamiltonian approaches, which were developed to describe free gravitational field(s) in the metric gravity, are formulated and discussed. By using the standard $\Gamma-\Gamma$ Lagrangian ${\cal L}_{\Gamma-\Gamma}$…

General Relativity and Quantum Cosmology · Physics 2024-11-21 Alexei M. Frolov

A recent work considered quantum simulation of Quantum Electrodynamics on a lattice in the Coulomb gauge with gauge degrees of freedom represented in the occupation basis in momentum space. Here we consider the more efficient representation…

Quantum Physics · Physics 2026-02-25 Xiaojun Yao

In this contribution we sketch a branch-cut quantum formulation of the Wheeler-DeWitt equation analytically continued to the complex plane. As a starting point, we base our approach on the Ho\v{r}ava-Lifshitz formulation of gravity, which…

General Relativity and Quantum Cosmology · Physics 2022-12-08 Peter O. Hess , César A. Zen Vasconcellos , José de Freitas Pacheco , Dimiter Hadjimichef , Benno Bodmann

In the Hamiltonian formulation, Quantum Field Theory calculations scale exponentially with spatial volume, making real-time simulations intractable on classical computers and motivating quantum computation approaches. In Hamiltonian…

High Energy Physics - Lattice · Physics 2025-11-03 Zong-Gang Mou , Bipasha Chakraborty

This article presents the lattice-smeared gravity phase space reduction defined by the cosmological gauge-fixing conditions. These conditions are specified to reduce the SU(2) symmetry and the spatial diffeomorphism invariance of the loop…

General Relativity and Quantum Cosmology · Physics 2021-05-28 Jakub Bilski

This work contains a detailed qualitative analysis, in General Relativity and in Loop Quantum Cosmology, of the dynamics in the associated phase space of a scalar field minimally coupled with gravity, whose potential mimics the dynamics of…

General Relativity and Quantum Cosmology · Physics 2017-11-09 Llibert Aresté Saló , Jaume Amorós , Jaume de Haro

Loop quantum cosmology(LQC) is the symmetric model of loop quantum gravity. In this paper, we generalize the structure of loop quantum cosmology to the theories with arbitrary spacetime dimensions. The isotropic and homogenous cosmological…

General Relativity and Quantum Cosmology · Physics 2016-10-13 Xiangdong Zhang

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

We present a detailed analysis of a quantum model for Loop Quantum Cosmology based on strict application of the Thiemann regularization algorithm for the Hamiltonian in Loop Quantum Gravity, extending the results presented previously in our…

General Relativity and Quantum Cosmology · Physics 2019-10-09 Mehdi Assanioussi , Andrea Dapor , Klaus Liegener , Tomasz Pawlowski

In this work we construct a noncommutative version of the Friedmann equations in the framework of effective loop quantum cosmology, extending and applying the ideas presented in a previous proposal by some of the authors. The model under…

General Relativity and Quantum Cosmology · Physics 2019-11-05 Luis Rey Díaz-Barrón , Abraham Espinoza-García , S. Pérez-Payán , J. Socorro

Unimodular gravity is based on a modification of the usual Einstein-Hilbert action that allows one to recover general relativity with a dynamical cosmological constant. It also has the interesting property of providing, as the momentum…

General Relativity and Quantum Cosmology · Physics 2014-11-21 Dah-Wei Chiou , Marc Geiller