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Main Authors: Mason, James, Jack, Robert L., Bruna, Maria
Format: Preprint
Published: 2024
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Online Access:https://arxiv.org/abs/2408.03932
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author Mason, James
Jack, Robert L.
Bruna, Maria
author_facet Mason, James
Jack, Robert L.
Bruna, Maria
contents The formation of dynamical patterns is one of the most striking features of nonequilibrium physical systems. Recent work has shown that such patterns arise generically from forces that violate Newton's third law, known as nonreciprocal interactions. These nonequilibrium phenomena are challenging for modern theories. Here, we introduce a model mixture of active (self-propelled) and passive (diffusive) particles amenable to exact mathematical analysis. We exploit state-of-the-art methods to derive exact hydrodynamic equations for the particle densities, which reveal effective nonreciprocal couplings between the active and passive species. We study the resulting collective behavior, including the linear stability of homogeneous states and phase coexistence in large systems. This reveals a novel phase diagram with the spinodal associated with active phase separation protruding through the associated binodal, heralding the emergence of dynamical steady states. We analyze these states in the thermodynamic limit of large system size, showing, for example, that sharp interfaces may travel at finite velocities, but traveling phase-separated states are forbidden. The model's mathematical tractability enables precise new conclusions beyond those available by numerical simulation of particle models or field theories.
format Preprint
id arxiv_https___arxiv_org_abs_2408_03932
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Dynamical patterns and nonreciprocal effective interactions in an active-passive mixture through exact hydrodynamic analysis
Mason, James
Jack, Robert L.
Bruna, Maria
Statistical Mechanics
The formation of dynamical patterns is one of the most striking features of nonequilibrium physical systems. Recent work has shown that such patterns arise generically from forces that violate Newton's third law, known as nonreciprocal interactions. These nonequilibrium phenomena are challenging for modern theories. Here, we introduce a model mixture of active (self-propelled) and passive (diffusive) particles amenable to exact mathematical analysis. We exploit state-of-the-art methods to derive exact hydrodynamic equations for the particle densities, which reveal effective nonreciprocal couplings between the active and passive species. We study the resulting collective behavior, including the linear stability of homogeneous states and phase coexistence in large systems. This reveals a novel phase diagram with the spinodal associated with active phase separation protruding through the associated binodal, heralding the emergence of dynamical steady states. We analyze these states in the thermodynamic limit of large system size, showing, for example, that sharp interfaces may travel at finite velocities, but traveling phase-separated states are forbidden. The model's mathematical tractability enables precise new conclusions beyond those available by numerical simulation of particle models or field theories.
title Dynamical patterns and nonreciprocal effective interactions in an active-passive mixture through exact hydrodynamic analysis
topic Statistical Mechanics
url https://arxiv.org/abs/2408.03932