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Autores principales: Barbieri, Santiago, Farré, Gerard
Formato: Preprint
Publicado: 2024
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Acceso en línea:https://arxiv.org/abs/2402.10764
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author Barbieri, Santiago
Farré, Gerard
author_facet Barbieri, Santiago
Farré, Gerard
contents We prove that the solutions of Hölder-differentiable Hamiltonian systems, associated to initial conditions in a small ball of radius $ρ>0$ around a Lagrangian, $(γ,τ)-$Diophantine, quasi-periodic torus, are stable over a time $t^{\text{stab}}\simeq 1/(|ρ|^{1+\frac{\ell-1}{τ+1}}|\ln ρ|^{\ell-1})$, where $\ell>2d+1, \ell \in \mathbb R$, is the regularity, and $d$ is the number of degrees of freedom. In the finitely differentiable case (for integer $\ell$), this result improves the previously known effective stability bounds around Diophantine tori. Moreover, by a previous work based on the Anosov-Katok construction, it is known that for any $\varepsilon>0$ there exists a $C^\ell$-Hamiltonian, with $ \ell\ge 3$, admitting a sequence of solutions starting at distance $ρ_n \to 0$ from a $(γ,τ)$-Diophantine torus that diffuse in a time of order $t^{\text{diff}}_n\simeq 1/(|ρ_n|^{1+\frac{\ell-1}{τ+1}+\varepsilon})$. Therefore the stability estimates that we show are optimal up to an arbitrarily small polynomial correction.
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spellingShingle Nearly-optimal effective stability estimates around Diophantine tori of Hölder Hamiltonians
Barbieri, Santiago
Farré, Gerard
Dynamical Systems
We prove that the solutions of Hölder-differentiable Hamiltonian systems, associated to initial conditions in a small ball of radius $ρ>0$ around a Lagrangian, $(γ,τ)-$Diophantine, quasi-periodic torus, are stable over a time $t^{\text{stab}}\simeq 1/(|ρ|^{1+\frac{\ell-1}{τ+1}}|\ln ρ|^{\ell-1})$, where $\ell>2d+1, \ell \in \mathbb R$, is the regularity, and $d$ is the number of degrees of freedom. In the finitely differentiable case (for integer $\ell$), this result improves the previously known effective stability bounds around Diophantine tori. Moreover, by a previous work based on the Anosov-Katok construction, it is known that for any $\varepsilon>0$ there exists a $C^\ell$-Hamiltonian, with $ \ell\ge 3$, admitting a sequence of solutions starting at distance $ρ_n \to 0$ from a $(γ,τ)$-Diophantine torus that diffuse in a time of order $t^{\text{diff}}_n\simeq 1/(|ρ_n|^{1+\frac{\ell-1}{τ+1}+\varepsilon})$. Therefore the stability estimates that we show are optimal up to an arbitrarily small polynomial correction.
title Nearly-optimal effective stability estimates around Diophantine tori of Hölder Hamiltonians
topic Dynamical Systems
url https://arxiv.org/abs/2402.10764