  Liquid $^3\mathrm{He}$ is a Fermi liquid that undergoes a BCS-type phase
transition to a spin-triplet superfluid, making it valuable for understanding
interacting fermions. When the temperature approaches the transition
temperature $T_{\mathrm{c}}$ from above, physical properties can be modified by
Cooper pair fluctuations, leading to deviations from the predictions of Fermi
liquid theory. We use nonequilibrium Green's function theory to study the role
of pair fluctuations on quasiparticle transport. The Boltzmann-Landau kinetic
equation, which describes the transport properties of Fermi liquids, acquires
corrections from the interaction of quasiparticles with pair fluctuations. As
an application, we study the effects of pair fluctuations on the propagation of
zero sound in liquid $^3\mathrm{He}$. We calculate the temperature-dependent
correction to the zero sound velocity due to pair fluctuations, and compare the
result with existing experimental data.
