Divergence Disease of the Pion-Baryon Interaction in Quark-Based Models

We examine the divergence of the baryon self-energy due to the pion-quark interaction in the chiral bag model and the cloudy bag model. For the pion-quark coupling only the lowest nonvanishing (i.e., the second) order is considered but the sum over virtual excitations of the quark is carried out. We point out that there are two types of divergence involved. One is the ultraviolet divergence that is common to local interactions, and the other is …