Regularity of Lipschitz free boundaries for weak solutions of Alt-Caffarelli type problems

Fuente: arXiv
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Main Authors: Domingo-Pasarin, Joan, Ros-Oton, Xavier
Format: Preprint
Published: 2026
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author Domingo-Pasarin, Joan
Ros-Oton, Xavier
author_facet Domingo-Pasarin, Joan
Ros-Oton, Xavier
contents Motivated by the Serrin problem, we study weak solutions of the generalised Alt-Caffarelli problem $-Δu = f$ in $Ω$, $u = 0$ on $\partialΩ$, $\partial_νu = Q$ on $\partialΩ$. Our main result establishes that if $Ω$ is Lipschitz, then it is actually $C^{\infty}$ (provided that $f$ and $Q$ are smooth). This was known before only for viscosity solutions. As a corollary, we obtain an alternative solution of Serrin's problem in the case of Lipschitz domains. We also discuss the characterisation of the regularity of Lipschitz domains in terms of their Poisson kernel.
format Preprint
id arxiv_https___arxiv_org_abs_2601_20493
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Regularity of Lipschitz free boundaries for weak solutions of Alt-Caffarelli type problems
Domingo-Pasarin, Joan
Ros-Oton, Xavier
Analysis of PDEs
35R35, 35B65, 31B05
Motivated by the Serrin problem, we study weak solutions of the generalised Alt-Caffarelli problem $-Δu = f$ in $Ω$, $u = 0$ on $\partialΩ$, $\partial_νu = Q$ on $\partialΩ$. Our main result establishes that if $Ω$ is Lipschitz, then it is actually $C^{\infty}$ (provided that $f$ and $Q$ are smooth). This was known before only for viscosity solutions. As a corollary, we obtain an alternative solution of Serrin's problem in the case of Lipschitz domains. We also discuss the characterisation of the regularity of Lipschitz domains in terms of their Poisson kernel.
title Regularity of Lipschitz free boundaries for weak solutions of Alt-Caffarelli type problems
topic Analysis of PDEs
35R35, 35B65, 31B05
url https://arxiv.org/abs/2601.20493