Domain Wall in Nambu-Jona-Lasinio Model
  The approximation for the NJL gap equation that was developed in our previous paper allows us to investigate vacuum inhomogeneities in the mean field approach. The simplest case of a domain wall is studied thoroughly. The Jackiw-Rebbi problem which arises in treatment of the fermions' interaction with the domain wall is solved explicitly and the entire spectrum of bound states is described. It is estabilished that under our assumptions no bound states exist at the domain wall, however higher-order corrections may make them appear. Thus existence of the quark bound states at domain walls may be a good test for subtle features of QCD. 
Sergii Kutnii
hep-th