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Main Authors: Cecchin, Alekos, Nikolaev, Paul
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2509.01266
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author Cecchin, Alekos
Nikolaev, Paul
author_facet Cecchin, Alekos
Nikolaev, Paul
contents For a system of mean field interacting diffusion on $\mathbb{T}^d$, the empirical measure $μ^N$ converges to the solution $μ$ of the Fokker-Planck equation. Refining this mean field limit as a Central Limit Theorem, the fluctuation process $ρ^N_t= \sqrt{N}( μ^N_t -μ_t)$ convergences to the solution $ρ$ of a linear stochastic PDE on the negative Sobolev space $H^{-λ-2}(\mathbb{T}^d)$. The main result of the paper is to establish a rate for such convergence: we show that $|\mathbb{E}[Φ(ρ_t^N)] - \mathbb{E}[Φ(ρ_t)]| = \mathcal{O}(\tfrac{1}{\sqrt{N}})$, for smooth functions on $H^{-λ-2}(\mathbb{T}^d)$. The strategy relies on studying the generators of the processes $ρ^N$ and $ρ$ on $H^{-λ-2}(\mathbb{T}^d)$, and thus estimating their difference. Among others, this requires to approximate in probability $ρ$ with solutions to stochastic diffential equations on the Hilbert space $H^{-λ-2}(\mathbb{T}^d)$. The flexibility of the approach permits to establish a rate for the fluctuations, not only in case of a regular drift, but also for the the 2D viscous Vortex model, governed by the Biot-Savart kernel, and for the repulsive Coulomb potential.
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publishDate 2025
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spellingShingle Convergence rate for Fluctuations of mean field interacting diffusion and application to 2D viscous Vortex model and Coulomb potential
Cecchin, Alekos
Nikolaev, Paul
Probability
For a system of mean field interacting diffusion on $\mathbb{T}^d$, the empirical measure $μ^N$ converges to the solution $μ$ of the Fokker-Planck equation. Refining this mean field limit as a Central Limit Theorem, the fluctuation process $ρ^N_t= \sqrt{N}( μ^N_t -μ_t)$ convergences to the solution $ρ$ of a linear stochastic PDE on the negative Sobolev space $H^{-λ-2}(\mathbb{T}^d)$. The main result of the paper is to establish a rate for such convergence: we show that $|\mathbb{E}[Φ(ρ_t^N)] - \mathbb{E}[Φ(ρ_t)]| = \mathcal{O}(\tfrac{1}{\sqrt{N}})$, for smooth functions on $H^{-λ-2}(\mathbb{T}^d)$. The strategy relies on studying the generators of the processes $ρ^N$ and $ρ$ on $H^{-λ-2}(\mathbb{T}^d)$, and thus estimating their difference. Among others, this requires to approximate in probability $ρ$ with solutions to stochastic diffential equations on the Hilbert space $H^{-λ-2}(\mathbb{T}^d)$. The flexibility of the approach permits to establish a rate for the fluctuations, not only in case of a regular drift, but also for the the 2D viscous Vortex model, governed by the Biot-Savart kernel, and for the repulsive Coulomb potential.
title Convergence rate for Fluctuations of mean field interacting diffusion and application to 2D viscous Vortex model and Coulomb potential
topic Probability
url https://arxiv.org/abs/2509.01266