Normalized solutions for the nonlinear Schrödinger equation with potential: the purely Sobolev critical case
Gianmaria Verzini, Junwei Yu
TL;DR
We address normalized solutions of the Sobolev-critical nonlinear Schrödinger equation with a weakly attractive potential on $\mathbb{R}^N$, $N\ge3$, under a mass constraint. The authors develop a constrained variational framework on the $L^2$-sphere and prove the existence of both a local minimizer (ground state) and a mountain-pass solution, with the mountain-pass result confined to $3\le N\le5$ and depending on smallness properties of the potential, the mass, and the energy landscape. Compactness is achieved through concentration-compactness arguments and a Jeanjean-type minimax construction, with a precise upper bound on the mountain-pass level that prevents dichotomy. The work also leverages a Hopf-Cole transform to obtain multiplicity results for ergodic Mean Field Games systems with potential and quadratic Hamiltonian, connecting PDE variational methods to game-theoretic models. Overall, the paper extends Sobolev-critical normalized-solution theory to nonhomogeneous potentials under low regularity and nonradial settings, delivering existence and multiplicity results under sharp, dimension-dependent conditions.
Abstract
We study the existence and multiplicity of positive solutions in $H^1(\mathbb{R}^N)$, $N\ge3$, with prescribed $L^2$-norm, for the (stationary) nonlinear Schrödinger equation with Sobolev critical power nonlinearity. It is well known that, in the free case, the associated energy functional has a mountain pass geometry on the $L^2$-sphere. This boils down, in higher dimensions, to the existence of a mountain pass solution which is (a suitable scaling of) the Aubin-Talenti function. In this paper, we consider the same problem, in presence of a weakly attractive, possibly irregular, potential, wondering (i) whether a local minimum solution appears, thus providing an orbitally stable family of solitons, and (ii) if the existence of a mountain-pass solution persists. We provide positive answers, depending on suitable assumptions on the potential and on the mass value. Moreover, by the Hopf-Cole transform, we give some applications of our results to the existence of multiple solutions to ergodic Mean Field Games systems with potential and quadratic Hamiltonian.
