Optimizers of the Finite-Rank Hardy-Lieb-Thirring Inequality for Hardy-Schrödinger Operator

Abstract: We study the following finite-rank Hardy-Lieb-Thirring inequality of Hardy-Schr\"odinger operator: \begin{equation*} \sum_{i=1}^N\left|\lambda_i\Big(-\Delta-\frac{c}{|x|^2}-V\Big)\right|^s\leq C_{s,d}^{(N)}\int_{\mathbb R^d}V_+^{s+\frac d2}dx, \end{equation*} where $N\in\mathbb N^+$, $d\geq3$, $0<c\leq c_*:=\frac{(d-2)^2}{4}$, $c_*\>0$ is the best constant of Hardy's inequality, and $V\in L^{s+\frac d2}(\mathbb R^d)$ holds for $s>0$. Here $\lambda_i\big(-\Delta-{c}{|x|^{-2}}-V\big)$ denotes the $i$-th min-max level of Hardy-Schr\"odinger operator $H_{c,V}:=-\Delta-{c}{|x|^{-2}}-V $ in $\mathbb R^d$, which equals to the $i$-th negative eigenvalue (counted with multiplicity) of $H_{c,V}$ in $\mathbb R^d$ if it exists, and vanishes otherwise. We analyze the existence and analytical properties of the optimizers for the above inequality.