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arXiv · 2505.19665

Spin-Waves without Spin-Waves: A Case for Soliton Propagation in Starling Flocks

Andrea Cavagna·Guido Cimino·Javier Cristín·Matteo Fiorini·Irene Giardina·Angelo Giustiniani·Tomás S. Grigera·Stefania Melillo·Roberto A. Palombella·Leonardo Parisi·Antonio Ponno·Mattia Scandolo·Zachary S. Stamler
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Abstract

Collective turns in starling flocks propagate linearly with negligible attenuation, indicating the existence of an underdamped sector in the dispersion relation. Beside granting linear propagation of the phase perturbations, the real part of the frequency should also yield a spin-wave form of the unperturbed correlation function. However, new high-resolution experiments on real flocks show that underdamped traveling waves coexist with an overdamped Lorentzian correlation. Theory and experiments are reconciled once we add to the dynamics a Fermi-Pasta-Ulam-Tsingou term.

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Andrea Cavagna, Guido Cimino, Javier Cristín, Matteo Fiorini, Irene Giardina, Angelo Giustiniani, Tomás S. Grigera, Stefania Melillo, Roberto A. Palombella, Leonardo Parisi, Antonio Ponno, Mattia Scandolo, Zachary S. Stamler. 2025-05-26. Spin-Waves without Spin-Waves: A Case for Soliton Propagation in Starling Flocks. https://arxiv.org/abs/2505.19665

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