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arXiv · 1501.07879

Braiding a flock: winding statistics of interacting flying spins

Jean-Baptiste Caussin·Denis Bartolo
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Abstract

When animal groups move coherently in the form of a flock, their trajectories are not all parallel, the individuals exchange their position in the group. In this Letter we introduce a measure of this mixing dynamics, which we quantify as the winding of the braid formed from the particle trajectories. Building on a paradigmatic flocking model we numerically and theoretically explain the winding statistics, and show that it is predominantly set by the global twist of the trajectories as a consequence of a spontaneous symmetry breaking.

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Jean-Baptiste Caussin, Denis Bartolo. 2015-06-26. Braiding a flock: winding statistics of interacting flying spins. https://doi.org/10.1103/physrevlett.114.258101

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