Solutions to the Fifth-Order KP II Equation Scatter
Peter Perry, Camille Schuetz
TL;DR
This work establishes global scattering for the fifth-order KPII equation with small initial data in $\dot{H}^{-\frac{1}{2},0}(\mathbb{R}^2)$, showing solutions converge to linear dynamics as $t\to\pm\infty$. Building on the KPII-3 framework of Hadac–Herr–Koch, the authors develop a robust $U^p$/$V^p$-type dispersive analysis tailored to the fifth-order dispersion, introducing adapted function spaces $\dot{Y}^{-\frac{1}{2}}$ and $\dot{Z}^{-\frac{1}{2}}$ and a modulation decomposition to control the bilinear nonlinearity. They prove key bilinear estimates and a fixed-point result in $\dot{Z}^{-\frac{1}{2}}[0,\infty)$, establish the convergence of the nonlinear Duhamel term to a scattering state $\varphi_+$, and show analytic wave operators $W_\pm$, $V_\pm$ linking initial and asymptotic data. The findings provide the first rigorous scattering result for KPII-5 and extend the non-resonant dispersive framework to higher-order multi-dimensional dispersive equations, with potential implications for broader nonlinearity-resonance analyses in dispersive PDEs.$
Abstract
The fifth-order KP II equation $$ \partial_t u + α\partial_x^3 u + β\partial_x^5 u + u \partial_x u + \partial_x^{-1} \partial_y^2u=0$$ ($β<0$, $α>0$) is a nonlinear dispersive equation that models long dispersive waves in two space dimensions. We prove that solutions of the fifth-order KP II equation scatter to solutions of the corresponding linear equation $$ \partial_t v + α\partial_x^3 v + β\partial_x^5 v + \partial_x^{-1} \partial_y^2 v = 0$$ for small data. Our proof uses builds on Hadac, Herr, and Koch's work (see ArXiv:0708.2011) on the third-order KP II equation.
