The Snake Instability of Ring Dark Solitons in Toroidally Trapped   Bose-Einstein Condensates
  We show that the onset of the snake instability of ring dark solitons requires a broken symmetry. We also elucidate explicitly the connection between imaginary Bogoliubov modes and the snake instability, predicting the number of vortex-anti-vortex pairs produced. In addition, we propose a simple model to give a physical motivation as to why the snake instability takes place. Finally, we show that tight confinement in a toroidal potential actually enhances soliton decay due to inhibition of soliton motion. 
Lauri Toikka, Kalle-Antti Suominen
cond-mat.quant-gas