Nonlinear scalar field equations with $L^2$ constraint: Mountain pass and symmetric mountain pass approaches

Jun Hirata, Kazunaga Tanaka

We study the existence of radially symmetric solutions of the following nonlinear scalar field equations in ${\mathbb{R}}^N$ ($N\ge 2$): $$ (*)_m \left\{ \eqalign{ -&Δu = g(u) -μu…