Burgers equation from non-thermal stationary states in nearly-integrable gases

Fuente: arXiv
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Main Authors: Lisiak, Paweł, Łebek, Maciej, Panfil, Miłosz
Format: Preprint
Published: 2025
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author Lisiak, Paweł
Łebek, Maciej
Panfil, Miłosz
author_facet Lisiak, Paweł
Łebek, Maciej
Panfil, Miłosz
contents When a gas of particles interacts with much a larger reservoir the density dynamics on large scales is typically governed by diffusion. We study this paradigmatic problem for weakly coupled integrable systems and show that this picture gets altered, when transport is investigated on top of long-lived non-thermal states. Remarkably, for states non-invariant under parity we find Burgers equation arising in the hydrodynamic limit. We explicitly compute the diffusion constant and nonlinear advective coefficient of the Burgers equation using a variant of the Chapman-Enskog theory. We find an excellent agreement between our theory and numerical simulations of a simplified model of stochastic two-body collisions. Our conclusions are based only on Galilean invariance, existence of a small system-bath coupling parameter and a small momentum exchange between the system and the bath particles during two-body scattering.
format Preprint
id arxiv_https___arxiv_org_abs_2512_09726
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Burgers equation from non-thermal stationary states in nearly-integrable gases
Lisiak, Paweł
Łebek, Maciej
Panfil, Miłosz
Statistical Mechanics
When a gas of particles interacts with much a larger reservoir the density dynamics on large scales is typically governed by diffusion. We study this paradigmatic problem for weakly coupled integrable systems and show that this picture gets altered, when transport is investigated on top of long-lived non-thermal states. Remarkably, for states non-invariant under parity we find Burgers equation arising in the hydrodynamic limit. We explicitly compute the diffusion constant and nonlinear advective coefficient of the Burgers equation using a variant of the Chapman-Enskog theory. We find an excellent agreement between our theory and numerical simulations of a simplified model of stochastic two-body collisions. Our conclusions are based only on Galilean invariance, existence of a small system-bath coupling parameter and a small momentum exchange between the system and the bath particles during two-body scattering.
title Burgers equation from non-thermal stationary states in nearly-integrable gases
topic Statistical Mechanics
url https://arxiv.org/abs/2512.09726