Stable critical point of the Robin function and bubbling phenomenon for a slightly subcritical elliptic problem

Abstract: In this paper, we deal with the boundary value problem $-\Delta u= |u|^{4/(n-2)}u/[\ln (e+|u|)]^\varepsilon$ in a bounded smooth domain $\Omega$ in $\mathbb{R}^n$, $n\geq 3$ with homogenous Dirichlet boundary condition. Here $\varepsilon>0$. Clapp et al. in Journal of Diff. Eq. (Vol 275) built a family of solution blowing up if $n\geq 4$ and $\varepsilon$ small enough. They conjectured in their paper the existence of sign changing solutions which blow up and blow down at the same point. Here we give a confirmative answer by proving that our slightly subcritical problem has a solution with the shape of sign changing bubbles concentrating on a stable critical point of the Robin function for $\varepsilon$ sufficiently small.