On critical Choquard equation with potential well

In this paper we are interested in the following nonlinear Choquard equation

$-Δ u+(λ V(x)-β)u = \big(|x|^{-μ}* |u|^{2_{μ}^{*}}\big)|u|^{2_{μ}^{*}-2}u\;\;\;\;\;\;\;\;\;\;\mbox{in}\;\; \mathbb{R}^N,$

where $λ, β∈\mathbb{R}^+$ , $0<μ<N, N≥4, 2_{μ}^{*} = (2N-μ)/(N-2)$ is the upper critical exponent due to the Hardy-Littlewood-Sobolev inequality and the nonnegative potential function $V∈ \mathcal{C}(\mathbb{R}^N, \mathbb{R})$ such that $Ω : = \mbox{int} V^{-1}(0)$ is a nonempty bounded set with smooth boundary. If $β>0$ is a constant such that the operator $-Δ +λ V(x)-β$ is non-degenerate, we prove the existence of ground state solutions which localize near the potential well int $V^{-1}(0)$ for $λ$ large enough and also characterize the asymptotic behavior of the solutions as the parameter $λ$ goes to infinity. Furthermore, for any $0<β<β_{1}$ , we are able to prove the existence of multiple solutions by the Lusternik-Schnirelmann category theory, where $β_{1}$ is the first eigenvalue of $-Δ$ on $Ω$ with Dirichlet boundary condition.