Monopole-antimonopole annihilation in a nematic liquid crystal

Abstract

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\ensuremath{\propto}(${\mathit{t}}_{0}$-t${)}^{\mathrm{\ensuremath{\alpha}}}$ with \ensuremath{\alpha}=0.5\ifmmode\pm\else\textpm\fi{}0.03.