Susceptibility of Orientationally-Ordered Active Matter to Chirality Disorder

TL;DR

This paper studies how two-dimensional active matter with long-range order responds to intrinsic chirality disorder, revealing that homogeneous phases become unstable in large systems while inhomogeneous phases can resist disorder.

Contribution

It combines particle-level models and hydrodynamic theories to analyze the stability of ordered active matter phases against chirality disorder, highlighting differences between homogeneous and inhomogeneous states.

Findings

Homogeneous phases are unstable to any chirality disorder in infinite systems.

Inhomogeneous coexistence phases can resist finite chirality disorder asymptotically.

Finite systems can resist some disorder, but stability changes in the thermodynamic limit.

Abstract

We investigate the susceptibility of long-range ordered phases of two-dimensional dry aligning active matter to population disorder, taken in the form of a distribution of intrinsic individual chiralities. Using a combination of particle-level models and hydrodynamic theories derived from them, we show that while in finite systems all ordered phases resist a finite amount of such chirality disorder, the homogeneous ones (polar flocks and active nematics) are unstable to any amount of disorder in the infinite-size limit. On the other hand, we find that the inhomogeneous solutions of the coexistence phase (bands) may resist a finite amount of chirality disorder even asymptotically.