Monopole-antimonopole annihilation in a nematic liquid crystal

We study the process of monopole-antimonopole (hedgehog-antihedgehog) annihilation in nematic liquid crystals theoretically and experimentally. We show, using a ``mini-max'' argument, that there exists a stable scaling solution to the nematodynamic equations describing this phenomenon, and find the solution numerically. We study the process experimentally in the uniaxial nematic, 4-cyano-4'-n-pentylbiphenyl, following a pressure jump or thermal quench. We confirm, over 3 orders of magnitude in time, the scaling-solution prediction for the pair separation D. We find D{∝}(t₀-t)^α with {α}=0.5±{}0.03.