Periodic space-time homogenisation of the $ϕ^4_2$ equation

Fuente: arXiv
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Main Authors: Hairer, Martin, Singh, Harprit
Format: Preprint
Published: 2023
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author Hairer, Martin
Singh, Harprit
author_facet Hairer, Martin
Singh, Harprit
contents We consider the homogenisation problem for the $ϕ^4_2$ equation on the torus $\mathbb{T}^2$, namely the behaviour as $\varepsilon \to 0$ of the solutions to the equation suggestively written as $$ \partial_t u_\varepsilon - \nabla\cdot {A}(x/\varepsilon,t/\varepsilon^2) \nabla u_\varepsilon = -u^3_\varepsilon +ξ$$ where $ξ$ denotes space-time white noise and $A: \mathbb{T}^2\times \mathbb{R}$ is uniformly elliptic, periodic and Hölder continuous. When the noise is regularised at scale $δ\ll 1$ we show that any joint limit $\varepsilon,δ\to 0$ recovers the classical dynamical $ϕ^4_2$ model. In certain regimes or if the regularisation is chosen in a specific way adapted to the problem, we show that the counterterms can be chosen as explicit local functions of $A$.
format Preprint
id arxiv_https___arxiv_org_abs_2311_15788
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Periodic space-time homogenisation of the $ϕ^4_2$ equation
Hairer, Martin
Singh, Harprit
Analysis of PDEs
Probability
60H17, 35B27
We consider the homogenisation problem for the $ϕ^4_2$ equation on the torus $\mathbb{T}^2$, namely the behaviour as $\varepsilon \to 0$ of the solutions to the equation suggestively written as $$ \partial_t u_\varepsilon - \nabla\cdot {A}(x/\varepsilon,t/\varepsilon^2) \nabla u_\varepsilon = -u^3_\varepsilon +ξ$$ where $ξ$ denotes space-time white noise and $A: \mathbb{T}^2\times \mathbb{R}$ is uniformly elliptic, periodic and Hölder continuous. When the noise is regularised at scale $δ\ll 1$ we show that any joint limit $\varepsilon,δ\to 0$ recovers the classical dynamical $ϕ^4_2$ model. In certain regimes or if the regularisation is chosen in a specific way adapted to the problem, we show that the counterterms can be chosen as explicit local functions of $A$.
title Periodic space-time homogenisation of the $ϕ^4_2$ equation
topic Analysis of PDEs
Probability
60H17, 35B27
url https://arxiv.org/abs/2311.15788