On Non-topological Solutions of the ${\bf G}_2$ Chern-Simons System

Abstract: For any rank 2 of simple Lie algebra, the relativistic Chern-Simons system has the following form: \begin{equation}\label{e001} \left{\begin{array}{c} \Delta u_1+(\sum_{i=1}^2K_{1i}e^{u_i} -\sum_{i=1}^2\sum_{j=1}^2e^{u_i}K_{1i}e^{u_j}K_{ij})=4\pi\displaystyle \sum_{j=1}^{N_1}\delta_{p_j}\ \Delta u_2+ (\sum_{i=1}^2K_{2i}e^{u_i}-\sum_{i=1}^2\sum_{j=1}^2e^{u_i}K_{2i}e^{u_j}K_{ij})=4\pi\displaystyle \sum_{j=1}^{N_2}\delta_{q_j} \end{array} \right.\mbox{in}\; \mathbb{R}^2, \end{equation} where $K$ is the Cartan matrix of rank $2$. There are three Cartan matrix of rank 2: ${\bf A}2$, ${\bf B}_2$ and ${\bf G}_2$. A long-standing open problem for \eqref{e001} is the question of the existence of non-topological solutions. In a previous paper \cite{ALW}, we have proven the existence of non-topological solutions for the ${\bf A}_2$ and ${\bf B}_2$ Chern-Simons system. In this paper, we continue to consider the ${\bf G}_2$ case. We prove the existence of non-topological solutions under the condition that either $N_2\displaystyle\sum{j=1}^{N_1} p_j=N_1\displaystyle \sum_{j=1}^{N_2} q_j $ or $N_2\displaystyle\sum_{j=1}^{N_1}p_j \not =N_1\displaystyle \sum_{j=1}^{N_2} q_j$ and $N_1,N_2>1$, $ |N_1-N_2|\neq 1$. We solve this problem by a perturbation from the corresponding ${\bf G}_2$ Toda system with one singular source. Combining with \cite{ALW}, we have proved the existence of non-topological solutions to the Chern-Simons system with Cartan matrix of rank $2$.