Modulation theory of Y- and X-wave Kadomtsev--Petviashvili solitons
This research uses modulation theory to study long-wavelength perturbations of 2-soliton solutions for the Kadomtsev-Petviashvili II (KP) equation. It treats complex soliton interactions as conjoined, semi-infinite modulated solitons. The work analyzes Y-shaped and X-shaped solutions, exploring how perturbations lead to geometric changes, spontaneous leg creation/deletion, and long-time asymptotic states like 3421 solitons.