An explicitly solvable NLS model with discontinuous standing waves

Riccardo Adami; Filippo Boni; Takaaki Nakamura; Alice Ruighi

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arXiv · 2502.03374

An explicitly solvable NLS model with discontinuous standing waves

Riccardo Adami·Filippo Boni·Takaaki Nakamura·Alice Ruighi

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Abstract

We study the NLS Equation on the line with a point interaction given by the superposition of an attractive delta potential with a dipole interaction, in the cases of $L^2$-subcritical and $L^2$-critical nonlinearity. For a subcritical nonlinearity we prove the existence and the uniqueness of Ground States at any mass. If the mass exceeds an explicit threshold, then there exists a positive excited state too. For the critical nonlinearity we prove that Ground States exist only in a specific interval of masses, while in a different interval excited states exist. We provide the value of the optimal constant in the Gagliardo-Nirenberg estimate and describe in the dipole case the branches of the stationary states as the strength of the interaction varies. Since all stationary states are explicitly computed, ours is a solvable model involving a non-standard interplay of a nonlinearity with a point interaction.

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Riccardo Adami, Filippo Boni, Takaaki Nakamura, Alice Ruighi. 2025-02-05. An explicitly solvable NLS model with discontinuous standing waves. https://arxiv.org/abs/2502.03374

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