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This work is devoted to the analysis of the linear Boltzmann equation in a bounded domain, in the presence of a force deriving from a potential. The collision operator is allowed to be degenerate in the following two senses: (1) the…

Analysis of PDEs · Mathematics 2014-02-03 Daniel Han-Kwan , Matthieu Léautaud

Metriplectic dynamical systems consist of a special combination of a Hamiltonian and a (generalized) entropy-gradient flow, such that the Hamiltonian is conserved and entropy is dissipated/produced (depending on a sign convention). It is…

Mathematical Physics · Physics 2026-04-06 C. Bressan , M. Kraus , O. Maj , P. J. Morrison

This paper uses dynamical invariants to describe the evolution of collisionless systems subject to time-dependent gravitational forces without resorting to maximum-entropy probabilities. We show that collisionless relaxation can be viewed…

Astrophysics of Galaxies · Physics 2015-06-03 Jorge Peñarrubia

A statistical theory is presented which allows to calculate the stationary state achieved by a driven system after a process of collisionless relaxation. The theory is applied to study an electron beam driven by an external electric field.…

Statistical Mechanics · Physics 2009-04-03 Felipe B. Rizzato , Renato Pakter , Yan Levin

We review and complete the existing literature on the kinetic theory of spatially homogeneous systems with long-range interactions taking collective effects into account. The evolution of the system as a whole is described by the…

Statistical Mechanics · Physics 2012-02-20 Pierre-Henri Chavanis

We perform a detailed study of the relaxation towards equilibrium in the Hamiltonian Mean-Field (HMF) model, a prototype for long-range interactions in $N$-particle dynamics. In particular, we point out the role played by the infinity of…

Statistical Mechanics · Physics 2009-11-10 Y. Y. Yamaguchi , J. Barr'e , F. Bouchet , T. Dauxois , S. Ruffo

From the microscopic theory, we derive a number conserving quantum kinetic equation, valid for a dilute Bose gas at any temperature, in which the binary collisions between the quasi-particles are mediated by phonon-like excitations (called…

Statistical Mechanics · Physics 2007-05-23 Patrick Navez

The paper presents a solution to the Boltzmann kinetic equation based on the construction of its discrete conservative model. Discrete analogue of the collision integral is presented as a contraction of a tensor, which is independent from…

Statistical Mechanics · Physics 2017-07-04 George Arabuli

Theory and simulations are used to study collisionless relaxation of a gravitational $N$-body system. It is shown that when the initial one particle distribution function satisfies the virial condition -- potential energy is minus twice the…

Statistical Mechanics · Physics 2008-08-25 Yan Levin , Renato Pakter , Felipe B. Rizzato

The homogeneous isotropic Boltzmann equation (HIBE) is a fundamental dynamic model for many applications in thermodynamics, econophysics and sociodynamics. Despite recent hardware improvements, the solution of the Boltzmann equation remains…

Computational Physics · Physics 2015-05-18 Pietro Asinari

Building on the development of a Hermite-Legendre analysis of one-dimensional gravitating collisionless systems, we present a technique for determining the steady states of such systems. This provides an important component for…

Astrophysics of Galaxies · Physics 2019-06-12 Robert J. Ragan , Eric I. Barnes

An understanding of how turbulent energy is partitioned between ions and electrons in weakly collisional plasmas is crucial for modelling many astrophysical systems. Using theory and simulations of a four-dimensional reduced model of…

Plasma Physics · Physics 2025-09-04 T. Adkins , R. Meyrand , J. Squire

In a collisionless, magnetized plasma, particles may stream freely along magnetic-field lines, leading to phase "mixing" of their distribution function and consequently to smoothing out of any "compressive" fluctuations (of density,…

Plasma Physics · Physics 2019-03-27 Romain Meyrand , Anjor Kanekar , William Dorland , Alexander A. Schekochihin

Stationary to pulsating soliton bifurcation analysis of the complex Ginzburg-Landau equation (CGLE) is presented. The analysis is based on a reduction from an infinite-dimensional dynamical dissipative system to a finite-dimensional model.…

Pattern Formation and Solitons · Physics 2009-11-11 E. N. Tsoy , N. Akhmediev

Relaxation processes in collisionless dynamics lead to peculiar behavior in systems with long-range interactions such as self-gravitating systems, non-neutral plasmas and wave-particle systems. These systems, adequately described by the…

Statistical Mechanics · Physics 2011-12-30 Pierre de Buyl , Pierre Gaspard

In the standard cosmological paradigm, structure formation occurs via gravitational encounters and mergers between galaxies and dark matter halos. These collisionless self-gravitating systems therefore prevail in a state of non-equilibrium…

Astrophysics of Galaxies · Physics 2024-02-15 Uddipan Banik

Among the various attempts to understand collisionless absorption of intense ultrashort laser pulses a variety of models has been invented to describe the laser beam target interaction. In terms of basic physics collisionless absorption is…

Plasma Physics · Physics 2015-03-16 T. Liseykina , P. Mulser , M. Murakami

This paper is concerned with the existence, shape and dynamical stability of infinite-energy equilibria for a general class of spatially homogeneous kinetic equations in space dimensions $d \geq 3$. Our results cover in particular…

Mathematical Physics · Physics 2013-09-30 Federico Bassetti , Lucia Ladelli , Daniel Matthes

Gravitational and electrostatic interactions are fundamental examples of systems with long-range interactions. Equilibrium properties of simple models with long-range interactions are well understood and exhibit exotic behaviors : negative…

Statistical Mechanics · Physics 2012-01-05 Pierre de Buyl

We present a theory of collisionless relaxation in systems with long-range interactions. Contrary to Lynden-Bell's theory of violent relaxation, which assumes global ergodicity and mixing, we show that quasi-stationary states (qSS) observed…

Statistical Mechanics · Physics 2025-04-28 Tarcísio Nunes Teles , Renato Pakter , Yan Levin