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OP-00442 Open

Global L2 scattering for the planar hyperbolic cubic Schrödinger equation

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For $u_0 \in L^2(\mathbb{R}^2)$ consider the cubic hyperbolic Schrödinger equation $$i\partial_t u + \partial_x^2 u - \partial_y^2 u + |u|^2 u = 0, \qquad u(0) = u_0,$$ on $\mathbb{R} \times \mathbb{R}^2$: the scalar equation, without the nonlocal term of the Davey–Stewartson systems. The linear flow $e^{it(\partial_x^2 - \partial_y^2)}$ satisfies the same Strichartz estimates as the standard Schrödinger flow, in particular $\|e^{it(\partial_x^2 - \partial_y^2)} f\|_{L^4(\mathbb{R} \times \mathbb{R}^2)} \le C \|f\|_{L^2}$, so by standard arguments the problem, which is mass-critical, is locally well-posed for all data in $L^2$ and has global solutions for small data. Dodson, Marzuola, Pausader and Spirn proved a profile decomposition in $L^2$ for this linear flow.

Problem. Does the local solution, unique in $C(I; L^2) \cap L^4(I \times \mathbb{R}^2)$ on compact time intervals $I$, extend for every $u_0 \in L^2(\mathbb{R}^2)$ to a global solution $u \in C(\mathbb{R}; L^2) \cap L^4_{\mathrm{loc}}(\mathbb{R} \times \mathbb{R}^2)$ that depends continuously on $u_0$ on compact time intervals, and are there $u_\pm \in L^2(\mathbb{R}^2)$ such that $$\lim_{t \to \pm\infty} \bigl\| u(t) - e^{it(\partial_x^2 - \partial_y^2)} u_\pm \bigr\|_{L^2} = 0 \, ?$$

Source: Saut and Wang (2024), Conjecture 1; stated earlier, without a source, as global well-posedness and scattering for all L² data, by Dodson, Marzuola, Pausader and Spirn (2018).

Imported from github.com/MColbrook/AIM.

Classification

Primary
AP — Analysis of PDEs
Secondary
MP
Keywords
AIM Open Applied Problems, dispersive equations, nonlinear Schrödinger equations, scattering

References

@article{saut2024,
  author  = {Saut, Jean-Claude and Wang, Yuexun},
  title   = {On the hyperbolic nonlinear {S}chr{\"o}dinger equations},
  journal = {Adv. Contin. Discrete Models},
  volume  = {2024},
  year    = {2024},
  pages   = {15},
  doi     = {10.1186/s13662-024-03811-w},
}
@article{dodson2018,
  author        = {Dodson, Benjamin and Marzuola, Jeremy L. and Pausader, Benoit and Spirn, Daniel P.},
  title         = {The profile decomposition for the hyperbolic {S}chr{\"o}dinger equation},
  journal       = {Illinois J. Math.},
  volume        = {62},
  number        = {1-4},
  year          = {2018},
  pages         = {293--320},
  doi           = {10.1215/ijm/1552442664},
  eprint        = {1708.08014},
  archivePrefix = {arXiv},
  note          = {Erratum: Illinois J. Math. 65 (2021), no. 1, 259--260, doi:10.1215/00192082-8886975},
}
@misc{aim-hyperbolic-cubic-nls-scattering,
  author       = {Brunton, Steve and Colbrook, Matthew J. and de Hoop, Maarten V. and Stepaniants, George and Townsend, Alex and Ward, Rachel},
  title        = {{Global L2 scattering for the planar hyperbolic cubic Schrödinger equation}},
  howpublished = {AIM --- Open Applied Problems, GitHub repository},
  year         = {2026},
  url          = {https://github.com/MColbrook/AIM/blob/a153f469ee0ea64e876b2ad97c79d252c19a3e22/problems/421-hyperbolic-cubic-nls-scattering.md},
  note         = {Entry 421 at commit a153f46, 2026-10-13},
}

Citing this problem

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OP-00442, "Global L2 scattering for the planar hyperbolic cubic Schrödinger equation", clopen.solutions.