Emergent collective behavior of cohesive, aligning particles

TL;DR

This paper presents a minimal model for cohesive, aligning particles that reveals six distinct collective states, demonstrating how simple torque interactions can produce complex, natural-like group behaviors.

Contribution

It introduces a novel minimal model with non-reciprocal torques for cohesion and alignment, uncovering multiple stable collective states and dynamics.

Findings

Six distinct collective states identified

States depend on initial conditions and stochasticity

Some states resemble natural collective behaviors

Abstract

Collective behavior is all around us, from flocks of birds to schools of fish. These systems are immensely complex, which makes it pertinent to study their behavior through minimal models. We introduce such a minimal model for cohesive and aligning self-propelled particles in which group cohesion is established through additive, non-reciprocal torques. These torques cause constituents to effectively turn towards one another. We additionally incorporate an alignment torque, which competes with the cohesive torque in the same spatial range. By changing the strength and range of these torque interactions, we uncover six states which we distinguish via their static and dynamic properties: a disperse state, a multiple worm state, a line state, a persistent worm state, a rotary worm state, and an aster state. Their occurrence strongly depends on initial conditions and stochasticity, so the model exhibits multistabilities. A number of the states exhibit collective dynamics which are reminiscent of those seen in nature.