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

TL;DR

This paper proves the uniqueness of topological solutions to a self-dual Chern-Simons equation on a torus with collapsing vortices under certain conditions, and links solution non-uniqueness between the plane and the torus.

Contribution

It extends existing uniqueness results for the Chern-Simons equation and constructs solutions on the torus that mirror solutions in the plane, revealing non-uniqueness implications.

Findings

Topological solutions are uniquely determined by vortex locations for small coupling parameter.

Constructed solutions on the torus approximate solutions in the plane with non-degenerate linearized operators.

Non-uniqueness in the plane implies non-uniqueness on the torus with collapsing vortices.

Abstract

We consider the following Chern-Simons equation, \begin{equation} \label{0.1} \Delta u+\frac 1{\varepsilon^2} e^u(1-e^u)=4\pi\sum_{i=1}^N \delta_{p_i^\varepsilon},\quad \text{in}\quad \Omega, \end{equation} where $\Omega$ is a 2-dimensional flat torus, $\varepsilon>0$ 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 $\varepsilon$ is small and the collapsing velocity of vortices $p_i^\varepsilon$ is slow enough or fast enough comparing with $\varepsilon$. 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 $u_\varepsilon$ 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.