Thermalization of Weakly Nonintegrable FPUT and Toda Dynamics: A Lyapunov Spectrum Perspective

2026/03/24 by Aniket Patra, Sergej Flach · 1 voice
Physics and Astronomy · #nlin.CD #nlin.SI

paper · pdf

Abstract

We study the thermalization slowing down of Fermi-Past-Ulam-Tsingou (FPUT) chains and of Toda chains with nonintegrable boundaries. We focus on the transition from FPUT to harmonic chains, from FPUT to Toda chains with fixed boundaries, and from nonintegrable open boundary Toda to integrable fixed boundary Toda. We compute the Lyapunov spectrum and analyze its scaling properties upon approaching integrable limits. We analyze the scaling of the largest Laypunov exponent, the rescaled Lyapunov spectrum, and the Kolmogorov-Sinai entropy. Using additional analytic arguments we demonstrate evidence that all three cases are operating in the regime of a Long Range Network of nonintegrable perturbations.

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Discussions

• Aniket Patra, Sergej Flach: Thermalization of Weakly Nonintegrable FPUT and Toda Dynamics: A Lyapunov Spectrum Perspective https://arxiv.org/abs/2603.22806 https://arxiv.org/pdf/2603.22806 https://arx [bsky, 0 points, 0 comments]

Related

• Thermalization of Classical Weakly Nonintegrable Many-Body Systems
• Measuring FPUT thermalization with Toda integrals
• Observation of prethermalization in weakly nonintegrable unitary maps
• Effective stochastic model for chaos in the Fermi-Pasta-Ulam-Tsingou chain
• Prethermalization in Fermi-Pasta-Ulam-Tsingou chains