Uniform restriction lower bounds and nongeodesic common nodal curves in integrable systems
Abstract
We construct a family of real analytic metrics on the two-torus, for which a fixed embedded nongeodesic circle is a nodal component of infinitely many real Laplace eigenfunctions. The examples address a question asked by Bourgain-Rudnick \cite{BR11}, and give a negative answer to the question asked by Toth-Zelditch \cite{TZ21} and Han \cite{Han}: whether a curve shared by infinitely many nodal sets must be geodesic. To explain the restriction obstruction, we prove uniform L2 lower bounds for joint eigenfunctions of quantum completely integrable (QCI) systems under transverse crossing and isolation of a tangential characteristic branch, then extend to multi-branch setting. The results are used to characterize the possible joint nodal curves in the Liouville tori, narrowing down the choices. Finally, the counterexample realizes one possibility for which cancellation happens exactly on a nongeodesic curve.
Related
- From the Optimal L2-Estimates (p,n) and (n,p)-Forms to Uniform Griffiths p-Positivity via Convolution and Restriction
- Cetraro lectures on integrable systems and moduli spaces of curves
- H-integrable solutions to 2d dimensional canonical systems
- Adiabatic Invariant Actions for Partially Integrable Systems
- Ricci flow of Integrable Sigma Models, Hitchin Systems and Quantum Seiberg-Witten theory
BibTeX
@misc{wu2026uniform,
title = {{Uniform restriction lower bounds and nongeodesic common nodal curves in integrable systems}},
author = {Xianchao Wu and Xiao Xiao},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.23836},
eprint = {2610.23836},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.23836},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Uniform restriction lower bounds and nongeodesic common nodal curves in integrable systems
AU - Xianchao Wu
AU - Xiao Xiao
PY - 2026
DA - 2026/10/16
PB - arXiv
DO - 10.48550/arxiv.2610.23836
UR - https://arxiv.org/abs/2610.23836
AB - We construct a family of real analytic metrics on the two-torus, for which a fixed embedded nongeodesic circle is a nodal component of infinitely many real Laplace eigenfunctions. The examples address a question asked by Bourgain-Rudnick \cite{BR11}, and give a negative answer to the question asked by Toth-Zelditch \cite{TZ21} and Han \cite{Han}: whether a curve shared by infinitely many nodal sets must be geodesic. To explain the restriction obstruction, we prove uniform L^2 lower bounds for joint eigenfunctions of quantum completely integrable (QCI) systems under transverse crossing and isolation of a tangential characteristic branch, then extend to multi-branch setting. The results are used to characterize the possible joint nodal curves in the Liouville tori, narrowing down the choices. Finally, the counterexample realizes one possibility for which cancellation happens exactly on a nongeodesic curve.
ER -