Asymptotic behavior of dark multi-solitons to the intermediate nonlinear Schrödinger equation

The intermediate nonlinear Schrödinger equation (abbreviated to (INS)) is a model equation for envelope waves in a deep stratified fluid and can be thought of as a generalization of the defocusing nonlinear Schrödinger equation. Furthermore, it possesses dark multi-solitons as well as the defocusing nonlinear Schrödinger equation. In this paper, we reveal the asymptotic behavior of dark multi-solitons to (INS). We also give the asymptotic behavior of bright multi-solitons to the intermediate long wave equation. Our analysis relies only on the explicit forms of multi-solitons obtained by Hirota’s bilinear method.