Radiation solution of the modified Korteweg–de Vries equation
An inverse scattering study of the radiation solution of the modified Korteweg–de Vries equation is carried out for a simple illustrative example. Specifically, extending the expansion approach (the reflection coefficient being expanded in powers of the area of the input potential) that we pioneered on the 3-wave interaction problem and recently applied to the study of sine-Gordon and sinh-Gordon dynamics, we obtain the complete spatial and temporal evolution of the modified KdV solution up to third order in the expansion. The solution and, in particular, its asymptotic (t → ∞) behaviour are discussed and a comparison is made with the asymptotic analysis of Ablowitz and Newell. The nonintegral contributions to the radiation solution are found to be in exact agreement as t → ∞ with Ablowitz and Newell's steepest descents approximation (evaluated for the same model) for the kernel of the Marchenko integral equation.