Form-factor interpretation of kink solutions to the nonlinear σ model

Kink solutions to the SU(2) nonlinear σ model in one time and two space dimensions are interpreted as matrix elements of the meson fields between states of a new, heavy, particle. These new particles are stable and carry a topologically conserved charge N (N=integer) which is odd under both charge conjugation and time reversal. To lowest order in a weak-coupling expansion their mass is proportional to |N|. Moreover, consistency of the form-factor interpretation is achieved by assigning to the particles an angular momentum L and electric charge Q obeying L=±NQ. More general solutions, apparently describing multiparticle states, are also discussed.