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Concentrating standing waves for the fractional nonlinear Schrödinger equation

We consider the semilinear equation $$ ε^{2s} (-Δ)^s u + V(x)u - u^p = 0, \quad u>0, \quad u\in H^{2s}(\R^N) $$ where $0<s<1,\ 1<p<\frac{N+2s}{N-2s}$, $ V(x)$ is a sufficiently smooth potential with $\inf_\R V(x)> 0$, and $ε>0$ is a small number. Letting $w_λ$ be the radial ground state of $(-Δ)^s w_λ+ λw_λ- w_λ^p=0$ in $H^{2s}(\R^N)$, we build solutions of the form $$ u_ε(x) \sim \sum_{i=1}^k w_{λ_i} ((x-ξ_i^ε)/ε),$$ where $λ_i = V(ξ_i^ε)$ and the $ξ_i^ε$ approach suitable critical points of $V$. Via a Lyapunov Schmidt variational reduction, we recover various existence results already known for the case $s=1$. In particular such a solution exists around $k$ nondegenerate critical points of $V$. For $s=1$ this corresponds to the classical results by Floer-Weinstein and Oh.