Self energy dynamic particle-hole

B The dynamic particle-hole self energy C The zeroth-order degenerate states D First order self energy... 

The dynamic part DJ E), which can be found in the literature [8], possesses poles related to resonances of two-particle-hole and higher excitations and a branch cut above the ionisation threshold. It has an analytic structure similar to the dynamic self energy (42) from the formal point of view. This is not surprising since the projection method for deriving the Feshbach Hamiltonian is formally similar to the derivation of Dyson s equation of Sec. Ill or in Refs. [26,9]. There, a partitioning was performed yielding a projection to the primary space spanned by the orthonormal T-states while Feshbach, on the other hand, projected onto the space spanned by the non-orthonormal states aj 5 ). 

---