MAGNETIC-MOMENT AND PERTURBATION-THEORY WITH SINGULAR MAGNETIC-FIELDS

The spectrum of a charged particle coupled to Aharonov-Bohm or anyon g auge fields displays a nonanalytic behavior in the coupling constant. Within perturbation theory, this gives rise to certain singularities w hich can be handled by adding a repulsive contact term to the Hamilton ian. We discuss the case of smeared hwr tubes with an arbitrary profil e and show that the contact term can be interpreted as the coupling of a magnetic moment spinlike degree of freedom to the magnetic field in side the flux tube. We also clarify the ansatz for the redefinition of the wave function.