Mass and Extremals Associated with the Hardy–Schrödinger Operator on Hyperbolic Space
AbstractWe consider the Hardy–Schrödinger operator {L_{\gamma}:=-\Delta_{\mathbb{B}^{n}}-\gamma{V_{2}}} on the Poincaré ball model of the hyperbolic space {\mathbb{B}^{n}} ({n\geq 3}). Here {V_{2}} is a radially symmetric potential, which behaves like the Hardy potential around its singularity at 0, i.e., {V_{2}(r)\sim\frac{1}{r^{2}}}. As in the Euclidean setting, {L_{\gamma}} is positive definite whenever {\gamma<\frac{(n-2)^{2}}{4}}, in which case we exhibit explicit solutions for the critical equation {L_{\gamma}u=V_{2^{*}(s)}u^{2^{*}(s)-1}} in {\mathbb{B}^{n},} where {0\leq s<2}, {2^{*}(s)=\frac{2(n-s)}{n-2}}, and {V_{2^{*}(s)}} is a weight that behaves like {\frac{1}{r^{s}}} around 0. In dimensions {n\geq 5}, the equation {L_{\gamma}u-\lambda u=V_{2^{*}(s)}u^{2^{*}(s)-1}} in a domain Ω of {\mathbb{B}^{n}} away from the boundary but containing 0 has a ground state solution, whenever {0<\gamma\leq\frac{n(n-4)}{4}}, and {\lambda>\frac{n-2}{n-4}(\frac{n(n-4)}{4}-\gamma)}. On the other hand, in dimensions 3 and 4, the existence of solutions depends on whether the domain has a positive “hyperbolic mass” a notion that we introduce and analyze therein.