Isolated singularities of positive solutions for Choquard equations in   sublinear case
  Our purpose of this paper is to study the isolated singularities of positive solutions to Choquard equation in the sublinear case $q \in (0,1)$   $$\displaystyle \ \ -\Delta u+ u =I_\alpha[u^p] u^q\;\;   {\rm in}\; \mathbb{R}^N\setminus\{0\},   % [2mm] \phantom{ }   \;\; \displaystyle \lim_{|x|\to+\infty}u(x)=0, $$ where $p >0, N \geq 3, \alpha \in (0,N)$ and $I_{\alpha}[u^p](x) = \int_{\mathbb{R}^N} \frac{u^p(y)}{|x-y|^{N-\alpha}}dy$ is the Riesz potential, which appears as a nonlocal term in the equation. We investigate the nonexistence and existence of isolated singular solutions of Choquard equation under different range of the pair of exponent $(p,q)$. Furthermore, we obtain qualitative properties for the minimal singular solutions of the equation. 
Huyuan Chen, Feng Zhou
math.AP