Numerical slope conjecture for ground states of the nonlinear Schrödinger equation on the unit ball

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Let B1B_1 be the unit ball, let β\beta denote the first Dirichlet eigenvalue parameter, and let QbQ_b be the least-energy (ground state) solution of the stationary nonlinear Schrödinger equation for b∈(−λ1,∞)b\in(-\lambda_1,\infty). Write M(Qb)M(Q_b) for its mass, let R\mathcal R be the corresponding ground state on the whole space, and let u(t)u(t) denote the solution with initial condition u0u_0. The standing wave associated with QbQ_b is eibtQbe^{ibt}Q_b. Slope conjecture. For d≥1d\geq1: (I) if 0<α<4/d0<\alpha<4/d, then for every b∈(−λ1,∞)b\in(-\lambda_1,\infty),

∂bM(Qb)>0,\partial_bM(Q_b)>0,

and eibtQbe^{ibt}Q_b is orbitally stable in H01(B1)H_0^1(B_1); (II) if α=4/d\alpha=4/d, the same positivity and orbital stability hold for every b∈(−λ1,∞)b\in(-\lambda_1,\infty), M(Qb)M(Q_b) increases monotonically with

lim⁡b→∞M(Qb)=M(R),\lim_{b\to\infty}M(Q_b)=M(\mathcal R),

and initial data satisfying M(u0)>M(R)M(u_0)>M(\mathcal R) produce solutions that blow up in finite time; (III) if α>4/d\alpha>4/d (with α<4/(d−2)\alpha<4/(d-2) when d≥3d\geq3), there is b∗∈(−λ1,∞)b^\ast\in(-\lambda_1,\infty) such that M(Qb)M(Q_b) increases to a maximum at b∗b^\ast and then decreases to M(R)M(\mathcal R), with ∂bM(Qb)>0\partial_bM(Q_b)>0 and orbital stability for b∈(−λ1,b∗)b\in(-\lambda_1,b^\ast), and ∂bM(Qb)<0\partial_bM(Q_b)<0 and instability for b∈(b∗,∞)b\in(b^\ast,\infty). The unstable branch may lead either to finite-time blow-up or to oscillation between two states. This conjecture is motivated by the Vakhitov–Kolokolov slope condition and the Grillakis–Shatah–Strauss stability method. The source says that these claims are confirmed numerically; the parser supplies no independent resolution status, so the conjecture is recorded as open.

References

Primary source

Christian Klein, Svetlana Roudenko and Nikola Stoilov, “Nonlinear Schrödinger equation on a unit ball in one and two dimensions”, arXiv:2510.24407 (2025).

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