ONE-PARTICLE AND 2-PARTICLE CURRENTS CREATED BY THE PHONON-ROTON EXCITATION IN HE-4

We have developed a variational many-body method for evaluation of the elementary excitations in quantum Bose fluids based on fluctuating, t ime dependent correlation functions and continuity equations. In the c ase of He-4 we have studied one and two-particle currents in the regio n of the phonon and roton excitations. We find that, the roton minimum is a resonance effect where the wavelength of the excitation matches with the wavelength of the oscillations caused by the two-particle cor relations. The patterns in the two-particle current, which develop wit h decreasing wavelength, change from a simple sound wave, through the backflow roils to a tube like structure. The backflow rolls become vis ible at, the wavenumbers k > 2.5 Angstrom(-1), and get elongated along the direction of motion forming tubes of tile atomic diameter when k > 3.2 Angstrom(-1).