Real-Spectrum Darboux Limits at Multiple Spatial Roots of the Coupled Fokas-Lenells System

Muchen Dong; Lei Wang

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arXiv · 2607.17955

Real-Spectrum Darboux Limits at Multiple Spatial Roots of the Coupled Fokas-Lenells System

Muchen Dong·Lei Wang

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Abstract

We investigate Darboux constructions generated by multiple spatial roots of the coupled Fokas-Lenells system on a plane-wave background. Nonreal double roots give regular one-fold transformations, whereas real double and triple roots require directional real-spectrum limits. We classify the admissible projective null sets, derive the leading spectral corrections, and establish global regularity. A critical background relation additionally produces a persistent zero branch, leading to distinct nonlocal plateaus along parabolic corridors, cubic level sets, and a characteristic line.

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Muchen Dong, Lei Wang. 2026-07-20. Real-Spectrum Darboux Limits at Multiple Spatial Roots of the Coupled Fokas-Lenells System. https://arxiv.org/abs/2607.17955

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