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We develop a relativistic framework to investigate the evolution of cosmological structures from the initial density perturbations to the highly nonlinear regime. Our approach involves proposing a procedure to match ``best-fit", exact…

General Relativity and Quantum Cosmology · Physics 2024-04-29 Przemyslaw Malkiewicz , Jan J. Ostrowski , Ismael Delgado Gaspar

In this letter, we stress that the simplest cosmological model consisting in a massless scalar field minimally coupled to homogeneous and isotropic gravity has an in-built $\SL(2,\mathbb{R})$ symmetry. Protecting this symmetry naturally…

General Relativity and Quantum Cosmology · Physics 2019-07-18 Jibril Ben Achour , Etera R. Livine

Following recent considerations of a non-zero value for the vacuum energy density and the realization that a simple Kantowski-Sachs model might fit the classical tests of cosmology, we study the qualitative behavior of three anisotropic and…

Astrophysics · Physics 2011-04-15 Paulo Aguiar , Paulo Crawford

Within the framework of loop quantum cosmology, there exists a semi-classical regime where spacetime may be approximated in terms of a continuous manifold, but where the standard Friedmann equations of classical Einstein gravity receive…

General Relativity and Quantum Cosmology · Physics 2009-11-10 James E. Lidsey

A generally anisotropic equation of state originally derived in the context of Newman-Janis rotating systems allows for vacuum energy at a specific density. In this paper we examine the possibility of using that equation of state for…

General Relativity and Quantum Cosmology · Physics 2023-09-08 Philip Beltracchi

It is quite relevant the extension of decoration transformation for quantum spin models since most of the real materials could be well described by Heisenberg type models. Here we propose an exact quantum decoration transformation and also…

Statistical Mechanics · Physics 2016-08-23 F. F. Braz , F. C. Rodrigues , S. M. de Souza , Onofre Rojas

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

A simple d-dimensional lattice model is proposed, incorporating some degree of frustration and thus capable of describing some aspects of molecular orientation in covalently bound molecular solids. For d=2 the model is shown to be…

Condensed Matter · Physics 2009-10-30 Fabio Siringo

The dynamics of a (3 + 1) dimensional homogeneous anisotropic universe is modified by Loop Quantum Cosmology and, consequently, it has generically a big bounce in the past instead of a big-bang singularity. This modified dynamics can be…

General Relativity and Quantum Cosmology · Physics 2016-11-11 S. Kalyana Rama

Our goal is to develop a more general scheme for constructing integrable lattice regularisations of integrable quantum field theories. Considering the affine Toda theories as examples, we show how to construct such lattice regularisations…

High Energy Physics - Theory · Physics 2015-07-27 C. Meneghelli , J. Teschner

In quantum mechanical many-body systems, long-range and anisotropic interactions promote rich spatial structure and can lead to quantum frustration, giving rise to a wealth of complex, strongly correlated quantum phases. Long-range…

Quantum chromodynamics (QCD) at non-zero isospin chemical potential is studied in a canonical approach by analyzing systems of fixed isospin number density. To construct these systems, we develop a range of new algorithms for performing the…

High Energy Physics - Lattice · Physics 2013-05-30 William Detmold , Kostas Orginos , Zhifeng Shi

We study homogeneous cosmological models in formulations of general relativity with cosmological constant based on a (complexified) connection rather than a spacetime metric, in particular in a first order theory obtained by integrating out…

General Relativity and Quantum Cosmology · Physics 2023-05-10 Steffen Gielen , Elliot Nash

The Cosmic Linear Anisotropy Solving System (CLASS) is a new accurate Boltzmann code, designed to offer a more user-friendly and flexible coding environment to cosmologists. CLASS is very structured, easy to modify, and offers a rigorous…

Instrumentation and Methods for Astrophysics · Physics 2011-05-17 Julien Lesgourgues

We solve the Wheeler-DeWitt equation for the minisuperspace of a cosmological model of Bianchi type I with a minimally coupled massive scalar field $\phi$ as source by generalizing the calculation of Lukash and Schmidt [1]. Contrarily to…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Michael Bachmann , Hans-Jurgen Schmidt

Intrinsic time-dependent invariants are constructed for classical, flat, homogeneous, anisotropic cosmology with a massless scalar material source. Invariance under the time reparameterization-induced canonical symmetry group is displayed…

General Relativity and Quantum Cosmology · Physics 2008-11-26 D. C. Salisbury , J. Helpert , A Schmitz

By imposing natural geometrical and kinematical conditions on a conformal Killing vector in Bianchi I spacetime, we show that a class of axisymmetric metrics admits a conformal motion. This class contains new exact solutions of Einstein's…

General Relativity and Quantum Cosmology · Physics 2009-10-28 Roy Maartens , Conrad Mellin

The spin-1 anisotropic Heisenberg model with a single-ion anisotropy is studied using the Oguchi's pair approximation. Although the theory is developed for lattices with general coordination number, we treat in detail the three-dimensional…

Statistical Mechanics · Physics 2007-05-23 Jan Dely , Jozef Strecka , Lucia Canova

We examine the behaviour of homogeneous, anisotropic space-times, specifically the locally rotationally symmetric Bianchi types $I$ and $VII_o$ in the presence of anisotropic matter. By finding an appropriate constant of the motion, and…

General Relativity and Quantum Cosmology · Physics 2016-04-29 David Sloan

We present results from a Monte Carlo simulation of non-compact lattice QED in 3 dimensions on a $16^3$ lattice in which an explicit anisotropy between $x$ and $y$ hopping terms has been introduced into the action. This formulation is…

High Energy Physics - Lattice · Physics 2007-05-23 Simon Hands , Iorwerth Owain Thomas
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