1. Many-body Green’s Functions
Exercise (15) Solution: 10 second order diagrams for the Green’s function

2. Equation of Motion for the Green’s Function
Exercise (16) Solution: 10 second order diagrams for the Green’s function
To obtain self energy, cut off Go at either end to leave stubs
There are six proper self-energy diagrams at second order

3. Evaluation of the Single Loop Bubble
Exercise (17) Solution: Same result by closing the contour in the lower half plane

4. Evaluation of the Single Loop Bubble
Exercise (18) Solution: continued
For x y