ADDITIVITY OF DIFFUSION-COEFFICIENTS FOR SOLITONS

The problem of soliton diffusion was studied by employing a Boltzmann type of kinetic equation. Two classes of scattering processes were con sidered: I) those preserving the integrability of the system and leadi ng to coordinate shifts without momentum change and II) those destroyi ng the integrability and leading to momentum transfer without coordina te shift. If was found that the total diffusion coefficient D is the s um of D-I and D-II. A physical explanation for this counterintuitive r esult is presented. As an example, the sine-Gordon system with impurit ies is considered.