  Motivated by the recently observed failure of the kinetic theory for the bulk
viscosity, we in turn revisit the shear viscosity and the thermal conductivity
of two-component fermions with a zero-range interaction both in two and three
dimensions. In particular, we show that their Kubo formula evaluated exactly in
the high-temperature limit to the lowest order in fugacity is reduced to the
linearized Boltzmann equation. Previously, such a microscopic derivation of the
latter was achieved only incompletely corresponding to the relaxation-time
approximation. Here, we complete it by resuming all contributions that are
naively higher orders in fugacity but become comparable in the zero-frequency
limit due to the pinch singularity, leading to a self-consistent equation for a
vertex function identical to the linearized Boltzmann equation. We then compute
the shear viscosity and the thermal conductivity in the high-temperature limit
for an arbitrary scattering length and find that the Prandtl number exhibits a
nonmonotonic behavior slightly below the constant value in the relaxation-time
approximation.

Quantum Gases;Statistical Mechanics;Nuclear Theory