https://doi.org/10.1140/epje/s10189-025-00482-7
Regular Article - Flowing Matter
Emergent collective behavior of cohesive, aligning particles
Division of Theoretical Physics Institute of Physics and Astronomy, Technische Universität Berlin, Hardenbergstr. 36, 10623, Berlin, Germany
Received:
29
January
2025
Accepted:
19
March
2025
Published online:
7
May
2025
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 a particle’s orientation vector to turn toward its neighbor so that it aligns with the separation vector. 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.
Supplementary Information The online version contains supplementary material available at https://doi.org/10.1140/epje/s10189-025-00482-7.
© The Author(s) 2025
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