Collisional Properties of a Polarized Fermi Gas with Resonant Interactions

Highly polarized mixtures of atomic Fermi gases constitute a novel Fermi liquid. We demonstrate how information on thermodynamic properties may be used to calculate quasiparticle scattering amplitudes even when the interaction is resonant and apply the results to evaluate the damping of the spin dipole mode. We estimate that under current experimental conditions the mode would be intermediate between the hydrodynamic and collisionless limits.

Figure 1

The scaled momentum relaxation rate $1/{\tilde{\tau }}_P$ at $T=0$ versus relative velocity $v$ in units of $k_{\mathrm{F}\downarrow }/m_{\downarrow }^{*}$. The full line is the result of numerical integration of Eq. (5), the dashed line is low-velocity result (7), and the dotted line is the high-velocity result (8).

Figure 2

The quantity $1/{\omega }_0{\tau }_P$ determining the damping of the dipole mode as a function of the amplitude of the oscillation for $T=0$ and $T=0.03T_{\mathrm{F}\uparrow }$. (For details see text.)