On the sharp quantitative stability of critical points of the Hardy-Littlewood-Sobolev inequality in $\mathbb{R}^{n}$ with $n\geq3$ (2501.19248v1)

Abstract: Assume $n\geq3$ and $u\in \dot{H}^1(\mathbb{R}^n)$. Recently, Piccione, Yang and Zhao \cite{Piccione-Yang-Zhao} established a nonlocal version of Struwe's decomposition in \cite{Struwe-1984}, i.e., if $u\geq 0$ and $\Gamma(u):=\left|\Delta u+D_{n,\alpha}\int_{\mathbb{R}^{n}}\frac{|u|^{p_{\alpha}}(y) }{|x-y|^{\alpha}}\mathrm{d}y |u|^{p_{\alpha}-2} u\right|_{H^{-1}} \rightarrow 0$, then $dist(u,\mathcal{T})\to 0$, where $dist(u,\mathcal{T})$ denotes the $\dot{H}^1(\mathbb{R}^n)$-distance of $u$ from the manifold of sums of Talenti bubbles. In this paper, we establish the nonlocal version of the quantitative estimates of Struwe's decomposition in Ciraolo, Figalli and Maggi \cite{CFM} for one bubble and $n\geq3$, Figalli and Glaudo \cite{Figalli-Glaudo2020} for $3\leq n\leq5$ and Deng, Sun and Wei \cite{DSW} for $n\geq6$ and two or more bubbles. We prove that for $n\geq 3$, $\alpha<n$ and $0<\alpha\leq 4$, [dist (u,\mathcal{T})\leq C\begin{cases} \Gamma(u)\left|\log \Gamma(u)\right|^{\frac{1}{2}}\quad&\text{if } \,\, n=6 \,\, \text{and} \,\, \alpha=4, \ \Gamma(u) \quad&\text{for any other cases.}\end{cases}] Furthermore, we show that this inequality is sharp for $N=6$ and $\alpha=4$.