English

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

Analysis of PDEs 2024-12-03 v2 Probability

Abstract

We consider the homogenisation problem for the ϕ24\phi^4_2 equation on the torus T2\mathbb{T}^2, namely the behaviour as ε0\varepsilon \to 0 of the solutions to the equation suggestively written as tuεA(x/ε,t/ε2)uε=uε3+ξ \partial_t u_\varepsilon - \nabla\cdot {A}(x/\varepsilon,t/\varepsilon^2) \nabla u_\varepsilon = -u^3_\varepsilon +\xi where ξ\xi denotes space-time white noise and A:T2×RA: \mathbb{T}^2\times \mathbb{R} is uniformly elliptic, periodic and H\"older continuous. When the noise is regularised at scale δ1\delta \ll 1 we show that any joint limit ε,δ0\varepsilon,\delta \to 0 recovers the classical dynamical ϕ24\phi^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 AA.

Keywords

Cite

@article{arxiv.2311.15788,
  title  = {Periodic space-time homogenisation of the $\phi^4_2$ equation},
  author = {Martin Hairer and Harprit Singh},
  journal= {arXiv preprint arXiv:2311.15788},
  year   = {2024}
}

Comments

Accepted version