Uniqueness of topological solutions of self-dual Chern-Simons equation with collapsing vortices

Abstract

We consider the following Chern-Simons equation, \begin{equation} \label{0.1} Δu+\frac 1{\varepsilon^2} e^u(1-e^u)=4π\sum_{i=1}^N δ_{p_i^\varepsilon},\quad \text{in}\quad Ω, \end{equation} where $\Omega$ is a 2-dimensional flat torus, $\epsilon >0$ is a coupling parameter and ${\delta }_p$ stands for the Dirac measure concentrated at $p$. In this paper, we proved that the topological solutions of \eqref{0.1} are uniquely determined by the location of their vortices provided the coupling parameter $\epsilon$ is small and the collapsing velocity of vortices $p_i^{\epsilon }$ is slow enough or fast enough comparing with $\epsilon$. This extends the uniqueness results of Choe \cite{Choe2005} and Tarantello \cite{Tarantello2007}. Meanwhile, for any topological solution $\psi$ defined in ${\mathbb{R}}^2$ whose linearized operator is non-degenerate, we construct a sequence topological solutions $u_{\epsilon }$ of \eqref{0.1} whose asymptotic limit is exactly $\psi$ after rescaling around $0$. A consequence is that non-uniqueness of topological solutions in ${\mathbb{R}}^2$ implies non-uniqueness of topological solutions on torus with collapsing vortices.