Roton Spectrum in Superfluid Mixture of He3 and He4

The spectrum of rotons in superfluid solutions of He3 and He4 is studied theoretically in the dilute limit of He3. We assume both the emission-absorption type and the scattering type interaction between rotons and He3 quasi-particles and calculate the shift and the width of the roton energy at its minimum as well as the diffusion constant of He3. The Raman scattering and the normal fluid density in the solutions are also studied. We then discuss the results of the measurements of the normal fluid density and of the Raman and the neutron scattering experiments on the basis of our analysis.