56 research outputs found
Shear viscosity and spin sum rules in strongly interacting Fermi gases
Fermi gases with short-range interactions are ubiquitous in ultracold atomic
systems. In the absence of spin-flipping processes the number of atoms in each
spin species is conserved separately, and we discuss the associated Ward
identities. For contact interactions the spin conductivity spectral function
sigma_s(omega) has universal power-law tails at high frequency. We derive the
spin f-sum rule and show that it is not affected by these tails in d<4
dimensions. Likewise the shear viscosity spectral function eta(omega) has
universal tails; in contrast they modify the viscosity sum rule in a
characteristic way.Comment: 7 pages, published versio
Transport in p-wave interacting Fermi gases
The scattering properties of spin-polarized Fermi gases are dominated by
p-wave interactions. Besides their inherent angular dependence, these
interactions differ from their s-wave counterparts as they also require the
presence of a finite effective range in order to understand the low-energy
properties of the system. In this article we examine how the shear viscosity
and thermal conductivity of a three-dimensional spin-polarized Fermi gas in the
normal phase depend on the effective range and the scattering volume in both
the weakly and strongly interacting limits. We show that although the shear
viscosity and thermal conductivity both explicitly depend on the effective
range near resonance, the Prandtl number which parametrizes the ratio of
momentum to thermal diffusivity does not have an explicit interaction
dependence both at resonance and for weak interactions in the low-energy limit.
In contrast to s-wave systems, p-wave scattering exhibits an additional
resonance at weak attraction from a quasi-bound state at positive energies,
which leads to a pronounced dip in the shear viscosity at specific
temperatures.Comment: 12 pages, 7 figures; published versio
- …