Shear viscosity and spin sum rules in strongly interacting Fermi gases
Physik Department, Technische Universität München, 85747 Garching, Germany
Revised: 15 January 2013
Published online: 11 March 2013
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 σs(ω) 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 η(ω) has universal tails; in contrast they modify the viscosity sum rule in a characteristic way.
© EDP Sciences, Springer-Verlag, 2013