Tachyon Condensation Due to Domain-Wall Annihilation in Bose-Einstein   Condensates
  We show theoretically that a domain-wall annihilation in two-component Bose-Einstein condensates causes tachyon condensation accompanied by spontaneous symmetry breaking in a two-dimensional subspace. Three-dimensional vortex formation from domain-wall annihilations is considered a kink formation in subspace. Numerical experiments reveal that the subspatial dynamics obey the dynamic scaling law of phase-ordering kinetics. This model is experimentally feasible and provides insights into how the extra dimensions influence subspatial phase transition in higher-dimensional space. 
Hiromitsu Takeuchi, Kenichi Kasamatsu, Makoto Tsubota and Muneto Nitta
cond-mat.quant-gas hep-ph hep-th