Soliton solutions corresponding to the higher-order non-elementary zeros and their asymptotic analysis for Sasa–Satsuma equation
摘要
Multi-geometric discrete spectral problem for Sasa–Satsuma equation is studied via Riemann–Hilbert approach. Summation representation of a new Darboux matrix is derived to remove pairs of the higher-order non-elementary zeros of the matrix Riemann–Hilbert problem simultaneously. Thus, the soliton solutions corresponding to the higher-order non-elementary zeros are constructed, which is also known as a weakly bound state. For those weakly bound states, results of asymptotic analysis show that: (1) interaction is elastic, and experiences the phase shift but no position shift; (2) asymptotic solitons are reflected instead of passing through each other during the interaction, and they diverge from each other logarithmically instead of linearly; (3) different from the solitons corresponding to the higher-order elementary zeros which describe the nonlinear superposition of weakly bound states with the same profile, profile of the solitons corresponding to the higher-order non-elementary zeros is asymmetrical about a certain straight line; (4) when the rank sequence is