Stationary phase corrections in the process of bosonization of   multi-quark interactions
  The functional integration over the auxiliary bosonic variables of cubic order related with the effective action of the Nambu -- Jona-Lasinio model with 't Hooft term has recently been obtained in the form of a loop expansion. Even numbers of loops contribute to the action, while odd numbers of loops are assigned to the measure. We consider the two-loop corrections and analyse their effect on the low-lying pseudoscalar and scalar mass spectra, quark condensates and weak decay constants. The results are compared to the leading order calculations and other approaches. 
Alexander A. Osipov, Brigitte Hiller, Joao Moreira, Alex H. Blin