Inhomogeneous Vacuum States in Nambu-Jona-Lasinio Model
  The mean field approach to the Nambu-Jona-Lasinio model is developed systematically. Approximate mean field action is obtained, based on the study of divergencies in the mean field action. A special scalar case of the approximate motion equations is studied and inhomogenouous solutions are discussed. It is shown that the model can have inhomogeneous vacuum configurations which leads to bound fermionic states. 
Sergii Kutnii
hep-th