Effective interactions of 3He quasiparticles in dilute solutions of 3He in superfluid 4He

Abstract

We compute the effective interaction at long wavelength of two opposite-spin 3He in superfluid 4He to second order in 3He-4He mass difference perturbation theory. The correction to the Bardeen, Baym, Pines result V(0) = − α2 m 4 s 2/n 4, in second order, is expressed exactly in terms of the dependence of the pure 4He kinetic energy on the 4He mass; this correction turns out to be an order of magnitude smaller than one would at first expect.