Origins of bright soliton transparency to Bogoliubov quasi-particles

Bogoliubov quasi-particles can pass through a one-dimensional bright soliton without reflection at all energies.\footnote{D. J. Kaup, Phys. Rev. A {\bf 42}, 5689 (1990).} Reflectionless properties of this kind usually originate from a supersymmetric structure of the corresponding Hamiltonian.\footnote{E. Witten, Nucl. Phys. B {\bf 188}, 513 (1981).}$^,$\footnote{C. V. Sukumar, J. Phys. A {\bf 18}, 2917 (1985).} However, we give a strong indication that in this case\footnotemark[1], the mathematical mechanism enabling full spectrum transparency of a scattering object does not fall into any of the conventional paradigms.