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To close the moment model deduced from kinetic equations, the canonical approach is to provide an approximation to the flux function not able to be depicted by the moments in the reduced model. In this paper, we propose a brand new closure…

Computational Physics · Physics 2021-02-16 Ruo Li , Weiming Li , Lingchao Zheng

We use a post-Gaussian variational approach to non-perturbatively study a general class of interacting bosonic quantum field theories with generalized dipole symmetries and fractonic behaviour. We find that while a Gaussian approach allows…

High Energy Physics - Theory · Physics 2023-08-16 Javier Molina-Vilaplana

We investigate classes of shear-free cosmological dust models with irrotational fluid flows within the framework of $f(T)$ gravity. In particular, we use the $1 + 3$ covariant formalism and present the covariant linearised evolution and…

General Relativity and Quantum Cosmology · Physics 2022-07-27 Heba Sami , Shambel Sahlu , Amare Abebe , Peter K. S. Dunsby

Fr\"ohlich model equations describing phonon condensation in open systems of biological relevance are here reinvestigated in a semi-classical non-equilibrium statistical context (with "semi-classical" it is meant that the evolution of the…

Biological Physics · Physics 2012-03-12 Jordane Preto

An approximation scheme for model disordered solids is proposed that leads to the fully analytical evaluation of the elastic constants under explicit account of the inhomogeneity (nonaffinity) of the atomic displacements. The theory is in…

Soft Condensed Matter · Physics 2011-08-23 Alessio Zaccone , Enzo Scossa-Romano

We investigate gravitational collapse of thick shell of fluid in the isotropic homogeneous universe without radiation described by the Einstein gravity with cosmological constant. We construct analytic solutions of this kind interpolating…

General Relativity and Quantum Cosmology · Physics 2022-09-07 Shuichi Yokoyama

We extend the standard model of forward-reverse shock (FS-RS) for gamma-ray burst (GRB) afterglow to more general cases. On one hand, we derive the analytical solution to the hydrodynamics of the shocks in two limiting cases, i.e., an…

High Energy Astrophysical Phenomena · Physics 2022-06-01 Ze-Lin Zhang , Ruo-Yu Liu , Jin-Jun Geng , Xue-Feng Wu , Xiang-Yu Wang

We apply a simple linearization, well known in solid state physics, to approximate the evolution at early times of cosmological N-body simulations of gravity. In the limit that the initial perturbations, applied to an infinite perfect…

Astrophysics · Physics 2009-11-11 M. Joyce , B. Marcos , A. Gabrielli , T. Baertschiger , F. Sylos Labini

The main purpose of our paper is to construct a viable Kaluza-Klein model satisfying the observable constraints. To this end, we investigate the six-dimensional model with spherical compactification of the internal space. Background matter…

General Relativity and Quantum Cosmology · Physics 2020-01-08 Ezgi Yalçınkaya , Alexander Zhuk

Gaussian process regression is a powerful Bayesian nonlinear regression method. Recent research has enabled the capture of many types of observations using non-Gaussian likelihoods. To deal with various tasks in spatial modeling, we benefit…

Machine Learning · Statistics 2025-08-26 Yuta Shikuri

This study explores singularity-free solutions to the static, spherical symmetric Einstein equations with the standard Schwarzschild solution as a boundary condition. Imposing the absence of curvature singularities and requiring…

General Relativity and Quantum Cosmology · Physics 2026-03-05 Sune Rastad Bahn , Michael Cramer Andersen

The microscopic dynamics of one-dimensional self-gravitating many-body systems is studied. We examine two courses of the evolution which has the isothermal and stationary water-bag distribution as initial conditions. We investigate the…

chao-dyn · Physics 2009-10-22 Toshio Tsuchiya , Tetsuro Konishi , Naoteru Gouda

We consider a two-dimensional MHD model describing the evolution of viscous, compressible and electrically conducting fluids under the action of vertical magnetic field without resistivity. Existence of global weak solutions is established…

Analysis of PDEs · Mathematics 2019-07-02 Yang Li , Yongzhong Sun

Evolution of quark-gluon plasma (QGP) near equilibrium can be described by the second-order relativistic viscous hydrodynamic equations. Consistent and analytically verifiable numerical solutions are critical for phenomenological studies of…

High Energy Physics - Phenomenology · Physics 2015-05-06 Long-Gang Pang , Yoshitaka Hatta , Xin-Nian Wang , Bo-Wen Xiao

We devise variants of classical nonconforming methods for symmetric elliptic problems. These variants differ from the original ones only by transforming discrete test functions into conforming functions before applying the load functional.…

Numerical Analysis · Mathematics 2017-10-11 Andreas Veeser , Pietro Zanotti

We study the quasi-stationary evolution of systems where an energetic confinement is unable to completely retain their constituents. It is performed an extensive numerical study of a gas whose dynamics is driven by binary encounters and its…

Statistical Mechanics · Physics 2007-05-23 L. Velazquez , H. Mosquera Cuesta , F. Guzman

We develop here a procedure to obtain regular static configurations as resulting from dynamical gravitational collapse of a massive matter cloud in general relativity. Under certain general physical assumptions for the collapsing cloud, we…

General Relativity and Quantum Cosmology · Physics 2016-03-10 Pankaj S. Joshi , Daniele Malafarina

We present a novel asymptotic-preserving semi-implicit finite element method for weakly compressible and incompressible flows based on compatible finite element spaces. The momentum is sought in an $H(\mathrm{div})$-conforming space,…

Numerical Analysis · Mathematics 2024-07-16 Enrico Zampa , Michael Dumbser

A description of the dynamics of a collisionless, self-gravitating fluid is developed and applied to follow the development of Large Scale Structures in the Universe. Such description takes on one of the assumptions of the Adhesion…

Astrophysics · Physics 2009-11-07 N. Menci

A new form of quasiclassical space-time dynamics for constrained systems reveals how quantum effects can be derived systematically from canonical quantization of gravitational systems. These quasiclassical methods lead to additional fields,…

General Relativity and Quantum Cosmology · Physics 2024-01-04 Kallan Berglund , Martin Bojowald , Manuel Diaz , Gianni Sims