Stability with explicit constants of the critical points of the fractional Sobolev inequality and applications to fast diffusion

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Main Authors: De Nitti, Nicola, König, Tobias
Format: Preprint
Published: 2022
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author De Nitti, Nicola
König, Tobias
author_facet De Nitti, Nicola
König, Tobias
contents We study the quantitative stability of critical points of the fractional Sobolev inequality. We show that, for a non-negative function $u \in \dot H^s(\mathbb R^N)$ whose energy satisfies $$\tfrac{1}{2} S^\frac{N}{2s}_{N,s} \le \|u\|_{\dot H^s(\mathbb R^N)} \le \tfrac{3}{2}S_{N,s}^\frac{N}{2s},$$ where $S_{N,s}$ is the optimal Sobolev constant, the bound $$ \|u -U[z,λ]\|_{\dot{H}^s(\mathbb R^N)} \lesssim \|(-Δ)^s u - u^{2^*_s-1}\|_{\dot{H}^{-s}(\mathbb R^N)}, $$ holds for a suitable fractional Talenti bubble $U[z,λ]$. {For functions $u$ which are close to Talenti bubbles, we give the sharp asymptotic value of the implied constant in this inequality.} As an application {of this}, we derive an explicit polynomial extinction rate for positive solutions to a fractional fast diffusion equation.
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institution arXiv
publishDate 2022
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spellingShingle Stability with explicit constants of the critical points of the fractional Sobolev inequality and applications to fast diffusion
De Nitti, Nicola
König, Tobias
Analysis of PDEs
We study the quantitative stability of critical points of the fractional Sobolev inequality. We show that, for a non-negative function $u \in \dot H^s(\mathbb R^N)$ whose energy satisfies $$\tfrac{1}{2} S^\frac{N}{2s}_{N,s} \le \|u\|_{\dot H^s(\mathbb R^N)} \le \tfrac{3}{2}S_{N,s}^\frac{N}{2s},$$ where $S_{N,s}$ is the optimal Sobolev constant, the bound $$ \|u -U[z,λ]\|_{\dot{H}^s(\mathbb R^N)} \lesssim \|(-Δ)^s u - u^{2^*_s-1}\|_{\dot{H}^{-s}(\mathbb R^N)}, $$ holds for a suitable fractional Talenti bubble $U[z,λ]$. {For functions $u$ which are close to Talenti bubbles, we give the sharp asymptotic value of the implied constant in this inequality.} As an application {of this}, we derive an explicit polynomial extinction rate for positive solutions to a fractional fast diffusion equation.
title Stability with explicit constants of the critical points of the fractional Sobolev inequality and applications to fast diffusion
topic Analysis of PDEs
url https://arxiv.org/abs/2211.10634