Dynamics of monopole annihilation by type-1/2 strings in a nematic liquid crystal

In uniaxial nematic liquid crystals, monopoles can be annihilated by type-1/2 strings. We present experimental measurements on the dynamics of this process as well as others, including loop collapses and monopole-pair annihilations. On dimensional grounds one expects the size of a collapsing structure in a nematic liquid crystal to scale as {τ}1/2 where {τ} is the time to annihilation. Indeed, type-1/2 loops and monopole-antimonopole pairs exhibit this kind of behavior. In contrast, for monopole annihilation by a type-1/2 string we find that the string-monopole separation scales as τ^α where {α}=0.629±{}0.006. {} 1996 The American Physical Society.