Exact calculation of the skyrmion lifetime in a ferromagnetic Bose   condensate
  The tunneling rate of a skyrmion in ferromagnetic spin-1/2 Bose condensates through an off-centered potential barrier is calculated exactly with the periodic instanton method. The prefactor is shown to depend on the chemical potential of the core atoms, at which level the atom tunnels. Our results can be readily extended to estimate the lifetime of other topological excitations in the condensate, such as vortices and monopoles. 
Yunbo Zhang, Wei-Dong Li, Lu Li, H.J.W. M\"uller-Kirsten