Kinetic theory of defect dynamics in active nematics

Active nematics are fluids of elongated active agents that exhibit self-sustained flows and liquid crystalline order. Realizations include suspensions of cytoskeletal filaments and motor proteins, epithelial tissue, and vibrated layers of granular rods. At high activity, active nematics exhibit spatio-temporal chaotic, turbulent-like flows with proliferation of topological defects. In this talk I will show that, focusing on the defects as the relevant quasiparticles driving the non-equilibrium dynamics, we can formulate a kinetic theory of the active defect gas and describe the onset of active turbulence as activity-driven defect unbinding. By coarse-graining the kinetic theory, we obtain a hydrodynamic description of the active defect gas.