Long time asymptotic for the Wadati-Konno-Ichikawa equation with finite density initial data

TL;DR

This paper analyzes the long-term behavior of solutions to the Wadati-Konno-Ichikawa equation with finite density initial data, confirming the soliton resolution conjecture using advanced asymptotic analysis methods.

Contribution

It develops a $ar{ ext{d}}$-generalized Deift-Zhou method to derive precise long-time asymptotics for the WKI equation with finite density data, confirming the soliton resolution conjecture.

Findings

Solution exhibits $N(I)$-soliton behavior on discrete spectrum.

Leading order decay term is $t^{-1/2}$ on continuous spectrum.

Residual error in asymptotics is $O(t^{-3/4})$.

Abstract

In this work, we investigate the Cauchy problem of the Wadati-Konno-Ichikawa (WKI) equation with finite density initial data. Employing the $\bar{\partial}$-generalization of Deift-Zhou nonlinear steepest descent method, we derive the long time asymptotic behavior of the solution $q(x,t)$ in space-time soliton region. Based on the resulting asymptotic behavior, the asymptotic approximation of the WKI equation is characterized with the soliton term confirmed by $N(I)$-soliton on discrete spectrum and the $t^{-\frac{1}{2}}$ leading order term on continuous spectrum with residual error up to $O(t^{-\frac{3}{4}})$. Our results also confirm the soliton resolution conjecture for the WKI equation with finite density initial data.