Functional integrals for condensed bose systems

We express an exact formulation for an interacting Bose system as a functional integration over complex functions. We propose a modification of the generating functional which leads to different limiting processes. The present article rests upon Bogoliubov's description on the explanation of the existence of the order-parameter in terms of quasiaverages arising from a symmetry breaking field. Discussions to determine the order-parameter function are also given. We indicate that the modified functional integral method is relevant to the theory of superfluidity. The derivation of Landau-Ginzburg type equation for the order-parameter is given.