Non-reciprocal forces and exceptional phase transitions in metric and topological flocks

Charles Packard; Daniel M. Sussman

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arXiv · 2208.09461

Non-reciprocal forces and exceptional phase transitions in metric and topological flocks

Charles Packard·Daniel M. Sussman

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Abstract

Many models of flocking involve alignment rules based on the mean orientation of neighboring particles, which we show introduces microscopic non-reciprocal interactions. In the absence of this microscopic non-reciprocity an exceptional phase transition is predicted at low noise strength within the Toner-Tu framework of polar aligning matter; we demonstrate this transition via large-scale numerical simulations. By coarse-graining the microscopic non-reciprocal forces found in more common models of flocking, we identify additional terms in a hydrodynamic description which lead to a highly ordered clustered phase in metric models and restore the homogeneous flocking phase in topological models.

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Charles Packard, Daniel M. Sussman. 2022-08-19. Non-reciprocal forces and exceptional phase transitions in metric and topological flocks. https://arxiv.org/abs/2208.09461

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