Three regimes of overtaking collision of two solitons

The classical problem concerning two solitons with different amplitudes moving in the same direction is reinvestigated in this study. It is well-known that the larger soliton will overtake the smaller one and both solitons will eventually regain their original profiles with different phase shifts. In previous works, it was found that two regimes are required to classify the collision type by observing the number of peaks at the symmetrical center plane. In the present Study, the third regime which Occurs under the condition 1/3 < R < 0.383 (R is the amplitude ratio) is found. Without this new finding, the collision type can not be exactly described.