学术报告（夏波 1.12）

We will first review the existence of ground states for a system of Klein-Gordon equations. We next recall Derrick's theorem on the stability of such solutions (for wave equations), which is based on the study the spectrum of the corresponding linearized operator. In this talk, we will give a complete description of the spectrum set for this linearized operator (in the radial case): the existence of a unique negative eigenvalue, no resonance, no embedded eigenvalue and the spectral gap property. This is based on a joint work with Yan Cui and Kai Yang.