Normalized Solutions to Schrödinger Equations with Critical Exponent and Mixed Nonlocal Nonlinearities

Abstract: We study the existence and nonexistence of normalized solutions $(u_a, \lambda_a)\in H^{1}(\mathbb{R}^N)\times \mathbb{R}$ to the nonlinear Schr\"{o}dinger equation with mixed nonlocal nonlinearities. This study can be viewed as a counterpart of the Brezis-Nirenberg problem in the context of normalized solutions to the nonlocal Schr\"{o}diger equation with a fixed $L^2$-norm $|u|_2=a>0$. The leading term is $L^2$-supercritical, that is, $p\in (\frac{N+\alpha+2}{N},\frac{N+\alpha}{N-2}]$, where the Hardy-Littlewood-Sobolev critical exponent $p=\frac{N+\alpha}{N-2}$ appears. We first prove that there exist two normalized solutions if $q\in (\frac{N+\alpha}{N},\frac{N+\alpha+2}{N})$ with $\mu >0$ small, that is, one is at the negative energy level while the other one is at the positive energy level. For $q=\frac{N+\alpha+2}{N}$, we show that there is a normalized ground state for $0<\mu < \tilde{\mu} $ and there exist no ground states for $\mu >\tilde{\mu}$, where $\tilde{\mu}$ is a sharp positive constant. If $q\in (\frac{N+\alpha+2}{N},\frac{N+\alpha}{N-2})$, we deduce that there exists a normalized ground state for any $\mu>0$. We also obtain some existence and nonexistence results for the case $\mu<0$ and $q\in (\frac{N+\alpha}{N},\frac{N+\alpha+2}{N}]$. Besides, we analyze the asymptotic behavior of normalized ground states as $\mu\rightarrow 0^{+}$.