An asymptotic formula for models with caustics
  We introduce an asymptotic formula for calculating quantum mechanical and quantum theoretical models with caustics, like the Nambu--Jona-Lasinio(NJL) model. This asymptotic formula is given by the form attached the extra term, which suppresses the divergence induced because of caustics, to the leading term of the WKB approximation. This formula guarantees validity of the mean field approximation of models with caustics. 
T. Sakaguchi