Collective Coordinates and the Absence of Yukawa Coupling in the   Classical Skyrme Model
  In systems with constraints, physical states must be annihilated by the constraints. We make use of this rule to construct physical asymptotic states in the Skyrme model. The standard derivation of the Born terms with asymptotic physical states shows that there is no Yukawa coupling for the Skyrmion. We propose a remedy tested in other solitonic models: A Wilsonian action obtained after integrating the energetic mesons and where the Skyrmion is a quantum state should have a Yukawa coupling. 
Fermin Aldabe