Model for quantum scattering of rotons. II. Two-dimensional interaction

A speculative roton Hamiltonian is used to calculate scattering cross sections in the two-dimensional problem. For the hard-cylinder interaction, one gets the same result as that obtained by the usual wave scattering in the high-energy limit. The variational calculation for the roton-vortex interactionP ·v_s yields the temperature-independent momentum-transfer cross section _T 8 Å, improving the results obtained before by other methods.