Fluctuation-Induced First Order Transition to Collective Motion

Fuente: arXiv
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Autori principali: Martin, David, Spera, Gianmarco, Chaté, Hugues, Duclut, Charlie, Nardini, Cesare, Tailleur, Julien, van Wijland, Frédéric
Natura: Preprint
Pubblicazione: 2024
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author Martin, David
Spera, Gianmarco
Chaté, Hugues
Duclut, Charlie
Nardini, Cesare
Tailleur, Julien
van Wijland, Frédéric
author_facet Martin, David
Spera, Gianmarco
Chaté, Hugues
Duclut, Charlie
Nardini, Cesare
Tailleur, Julien
van Wijland, Frédéric
contents The nature of the transition to collective motion in assemblies of aligning self-propelled particles remains a long-standing matter of debate. In this article, we focus on dry active matter and show that weak fluctuations suffice to generically turn second-order mean-field transitions into a `discontinuous' coexistence scenario. Our theory shows how fluctuations induce a density-dependence of the polar-field mass, even when this effect is absent at mean-field level. In turn, this dependency on density triggers a feedback loop between ordering and advection that ultimately leads to an inhomogeneous transition to collective motion and the emergence of inhomogeneous travelling bands. Importantly, we show that such a fluctuation-induced first order transition is present in both metric models, in which particles align with neighbors within a finite distance, and in `topological' ones, in which alignment is based on more complex constructions of neighbor sets. We compute analytically the noise-induced renormalization of the polar-field mass using stochastic calculus, which we further back up by a one-loop field-theoretical analysis. Finally, we confirm our analytical predictions by numerical simulations of fluctuating hydrodynamics as well as of topological particle models with either k-nearest neighbors or Voronoi alignment.
format Preprint
id arxiv_https___arxiv_org_abs_2402_05078
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Fluctuation-Induced First Order Transition to Collective Motion
Martin, David
Spera, Gianmarco
Chaté, Hugues
Duclut, Charlie
Nardini, Cesare
Tailleur, Julien
van Wijland, Frédéric
Soft Condensed Matter
Statistical Mechanics
The nature of the transition to collective motion in assemblies of aligning self-propelled particles remains a long-standing matter of debate. In this article, we focus on dry active matter and show that weak fluctuations suffice to generically turn second-order mean-field transitions into a `discontinuous' coexistence scenario. Our theory shows how fluctuations induce a density-dependence of the polar-field mass, even when this effect is absent at mean-field level. In turn, this dependency on density triggers a feedback loop between ordering and advection that ultimately leads to an inhomogeneous transition to collective motion and the emergence of inhomogeneous travelling bands. Importantly, we show that such a fluctuation-induced first order transition is present in both metric models, in which particles align with neighbors within a finite distance, and in `topological' ones, in which alignment is based on more complex constructions of neighbor sets. We compute analytically the noise-induced renormalization of the polar-field mass using stochastic calculus, which we further back up by a one-loop field-theoretical analysis. Finally, we confirm our analytical predictions by numerical simulations of fluctuating hydrodynamics as well as of topological particle models with either k-nearest neighbors or Voronoi alignment.
title Fluctuation-Induced First Order Transition to Collective Motion
topic Soft Condensed Matter
Statistical Mechanics
url https://arxiv.org/abs/2402.05078