Perturbation theoretic calculation of the one-particle Green's functions is studied for a large system of bosons at zero temperature. We start from a splitting of the Hamiltonian in which the unperturbed part is chosen to be diagonal in the Bogolyubov quasi particle operators. The self-consistent form of the perturbation expansion required by the appearance of inequivalent representations of canonical commutation relations is formulated and discussed.
ASJC Scopus subject areas
- Nuclear and High Energy Physics