We consider two-component fermions with a zero-range interaction in two and three dimensions and study their transport coefficients—shear viscosity, bulk viscosity, and thermal conductivity—for an arbitrary scattering length. In order to carry out reliable analysis in the strongly correlated regime, such as near the unitarity limit, we employ the quantum virial expansion. The quantum virial expansion is applicable to the high-temperature regime and has been actively used as a non-perturbative method in ultracold-atom physics.
In this talk, I will first review the quantum virial expansion for the resonating fermions and then introduce previous results for the transport coefficients. Next, I will show that the Kubo formula of the shear viscosity and the thermal conductivity evaluated at the lowest order in the quantum virial expansion is reduced to the linearized Boltzmann equation [1]. I will also discuss that the bulk viscosity cannot be calculated from the kinetic theory even in the high-temperature regime [2].

References
[1] KF & Y. Nishida, PRA 103, 053320 (2021).
[2] KF & Y. Nishida, PRA 102, 023310 (2020).