Noncommuting Momenta of Topological Solitons
  We show that momentum operators of a topological soliton may not commute among themselves when the soliton is associated with the second cohomology $H^2$ of the target space. The commutation relation is proportional to the winding number, taking a constant value within each topological sector. The noncommutativity makes it impossible to specify the momentum of a topological soliton, and induces a Magnus force. 
Haruki Watanabe, Hitoshi Murayama
hep-th cond-mat.other cond-mat.quant-gas hep-ph