The variable-length stem structures in three-soliton resonance of the Kadomtsev-Petviashvili II equation
Feng Yuan, Jingsong He, Yi Cheng
TL;DR
This work analyzes variable-length stem structures that arise during resonant interactions of KPII multi-solitons. Using the KPII equation in its tau-function form and explicit 3-soliton solutions, the authors perform rigorous asymptotic analysis for 2-resonant and 3-resonant cases, deriving trajectories, endpoints, and amplitudes of stem structures and detailing soliton reconnection dynamics. They classify resonances as strong, weak, or mixed according to phase-shift limits $a_{ij}\to0$ or $\infty$, and provide complete asymptotic characterizations, including corrections and extensions to prior results. The findings deepen the understanding of localized structures within KPII resonant networks and offer analytical tools for predicting stem evolution and topological transitions in high-order soliton interactions.
Abstract
The stem structure is a localized feature that arises during high-order soliton interactions, connecting the vertices of two V-shaped waveforms. The interaction of resonant 3-solitons is accompanied by soliton reconnection phenomena, characterized by the disappearance and reconnection of stem structures. This paper investigates variable-length stem structures in resonant 3-soliton solutions of the Kadomtsev-Petviashvili II (KPII) equation, focusing on both 2-resonant and 3-resonant 3-soliton cases. Depending on the phase shift tends to plus/minus infinity, different types of resonances are identified, including strong resonance, weak resonance, and mixed (strong-weak) resonance. We derive and analyze the asymptotic forms and explicit expressions for the soliton arm trajectories, velocities, as well as the endpoints, length, and amplitude of the stem structures. A detailed comparison is made between the similarities and differences of the stem structures in the 2-resonant and 3-resonant solitons. In addition, we provide a comprehensive and rigorous analysis of both the asymptotic behavior and the structural properties of the stems.
