Uniqueness of normalized ground states for NLS models
Hichem Hajaiej, Linjie Song
TL;DR
This work addresses the uniqueness of normalized ground states for nonlinear Schrödinger-type equations by developing two general frameworks. The first method uses a sign-change analysis of the λ-derivative along a global solution branch to obtain strict monotonicity of the $L^2$ mass and, hence, ground-state uniqueness on each mass level; the second method connects the differentiability of the minimal energy $m(c)$ on the mass constraint set $S_c$ with the uniqueness of ground states via the set of corresponding Lagrange multipliers. The authors apply these approaches to a broad class of problems, including with or without potentials, fractional operators, and inhomogeneous nonlinearities on the unit ball, deriving existence, mass-monotonicity, uniqueness, and orbital stability results across mass-subcritical, critical, and supercritical regimes. The results unify and extend known outcomes, providing conditions under which normalized ground states are unique and orbitally stable, with explicit constructions of global solution branches. The work thus advances the understanding of how spectral and variational structures govern standing-wave stability in nonlinear dispersive PDEs. $
Abstract
We present two methods to prove the uniqueness of normalized ground states. We will first discuss the key ideas and ingredients of each method. Then, we will apply them to various classes of PDEs. Our approach is applicable to other operators, domains and nonlinearities provided that some hypotheses are satisfied.
