Metastability of Constant-Density Flocks

Abstract

We study numerically the Toner-Tu field theory where the density field is maintained constant, a limit case of "Malthusian" flocks for which the asymptotic scaling of correlation functions in the ordered phase is known exactly. While we confirm these scaling laws, we also show that such constant-density flocks are metastable to the nucleation of a specific defect configuration, and are replaced by a globally disordered phase consisting of asters surrounded by shock lines that constantly evolves and remodels itself. We demonstrate that the main source of disorder lies along shock lines, rendering this active foam fundamentally different from the corresponding equilibrium system. We thus show that in the context of active matter also, a result obtained at all orders of perturbation theory can be superseded by non-perturbative effects, calling for a different approach.

6 pages, 4 figures

References in corpus (5)

• Novel type of phase transition in a system of self-driven particles
• Pattern formation of microtubules and motors: inelastic interaction of polar rods
• Critical Phenomenon of the Order-Disorder Transition in Incompressible Flocks
• Small Obstacle in a Large Polar Flock
• Active polar flock with birth and death

Cited by in corpus (13)

• Self-Aligning Polar Active Matter
• Flocking of two unfriendly species: The two-species Vicsek model
• Metastability of Discrete-Symmetry Flocks
• Phase Coexistence in Nonreciprocal Quorum-Sensing Active Matter
• Emergent complex phases in a discrete flocking model with reciprocal and non-reciprocal interactions
• Minimum scaling model and exact exponents for the Nambu-Goldstone modes in the Vicsek Model
• The XY model with vision cone: non-reciprocal vs. reciprocal interactions
• Don't look back: Ordering and defect cloaking in non-reciprocal lattice XY models
• Thermodynamic constraints and exact scaling exponents of flocking matter
• Supramolecular assemblies in active motor-filament systems: micelles, bilayers, and foams
• Coarsening of topological defects in 2D polar active matter
• Stability of discrete-symmetry flocks: sandwich state, traveling domains and motility-induced pinning
• Bubble formation in active binary mixture model